Fix Slow Outlook Email Address AutoComplete

Outlook Auto Complete can be slow. The good news is I have the fix for older versions of Outlook.

Outlook AutoComplete can be slow. The good news is I have the fix. Thanks to a bug with McAfee, Outlook 2007 (and possibly 2003) users will experience severe lockups (3-10 seconds) and delays while typing in email addresses or deleting email addresses in Outlook. The larger your Outlook AutoComplete cache file (.nk2), the longer you will wait.  Before I found this fix, I was ready to remove Outlook 2007 and go back to 2003.

Let’s get to the Fix:

The issue is a result of how the new McAfee Buffer Overflow Protection interacts with the Outlook automatic completion feature.

To fix the problem you need to tell McAfee to Exclude outlook.exe from the Buffer Overflow protection:

Add an exclusion locally for outlook.exe under Buffer Overflow Protection settings:

  1. Click, Start, Programs, McAfee, VirusScan Console.
  2. Right-click on Buffer Overflow Protection and Select Properties.
  3. With the Buffer Overflow Protection tab selected Click Add.
  4. In the Process Name field type, the following: outlook.exe then click OK.
  5. Click Apply then OK to close the Buffer Overflow Exclusions window.
  6. Fixed!

Additional Background/Information

1. Please note, in my case, my notebook was installed with:

  • Microsoft Vista Enterprise Edition
  • Microsoft Outlook 2007 (errr… Office 2007)
  • McAfee VirusScan Enterprise 8.5.0i

2. If your computer is attached to a company network, there is a chance that these settings will be grayed out. In these cases, your computer is probably managed by McAfee’s enterprise management product (EPO) or, when McAfee VirusScan was installed, a password was used to lock the config. In either of these cases, you will need to contact your Systems Administrator or Helpdesk for assistance.

3. When I first ran into this problem, the first thing I did was delete my .nk2 file (Check here for instructions on where to find the .nk2 file) thinking that perhaps mine had become corrupt.  Although this was a “temporary” fix, once the file grew I began having performance problems again with the auto-complete function. Just an FYI.



  1. Marcel

    July 30, 2007 at 12:43 am

    Thanks, this solved an extremely irritating problem.

  2. MrGroove

    July 30, 2007 at 8:42 am

    Trust me, I understand 110% Marcel!

    I spend 1/2 my day in outlook these days… … so before the fix I was ready to lose my mind. Then there’s the users who were beginning to riot in the halls with pitchforks…….

    Glad the article helped you out!

  3. Mike

    August 23, 2007 at 2:01 am

    You deserve a medal. This was driving me completely potty – was starting to think I would never find an answer.


  4. MrGroove

    August 23, 2007 at 8:25 am

    Thanks Mike. Personally, had it taken another “day” for me to find the fix I was ready to uninstall Outlook 2007 and fallback to Outlook 2003 on my work machine…

    Glad it helped you out!

  5. MonsterP

    August 24, 2007 at 2:03 am

    Thanks MrGroove,
    I’m so glad I found your tip. Slow autocomplete has been crippling me since I upgraded and getting worse.
    Excellent advice.


  6. Leo

    September 5, 2007 at 8:10 am

    Thanks! for this fix!
    It eluded me for several months how to fix this.
    Now Outlook works just fine again.

  7. Converted

    September 12, 2007 at 6:31 pm


    You just saved my life. My entire IT org. was working on this STUPID problem! Thank you very much mrgroove!

  8. Jameson

    September 24, 2007 at 2:18 pm

    Life Saver!!! Thanks you very much.

  9. MrGroove

    September 24, 2007 at 5:28 pm

    Glad the article helped you out!

  10. simonsays

    October 10, 2007 at 4:51 am

    This morning I came very close to throwing my monitor through the window. Thank you *so* much for this fix!

  11. MrGroove

    October 10, 2007 at 7:54 am

    Excellent! Welcome to the site Simon.

  12. Aryn

    October 17, 2007 at 2:36 am

    This fixed worked a charm thank you!

    Machine setup:
    Win XP Pro SP2
    McAfee 8.5.0i
    Outlook 2007 with all updates
    Original NK2 file size is\was 1.2MB

    Thanks again, would have probably ended up reinstalling Outlook in the end.

  13. MrGroove

    October 18, 2007 at 10:24 am

    Excellent! Aryn! And welcome to the site!

  14. Mike

    October 23, 2007 at 6:49 am

    Good job, thanks!

  15. Mark

    October 29, 2007 at 8:05 pm

    I don’t see a “Buffer Overflow Protection” tab in the VirusScan console.
    My operating system is Vista…if that helps.
    Any ideas???

  16. MrGroove

    October 30, 2007 at 5:23 am

    Hi Mark and Welcome to the site!
    What version of VirusScan are you running? You should be able to right click on your virusScan shield and click “about” to get the version number.

  17. Mark

    October 30, 2007 at 3:12 pm

    Thanks for the prompt response.
    I’m running version 8.5.0i

  18. MrGroove

    October 30, 2007 at 11:23 pm

    No problem Mark. For this kind of Tech support, I think the forum is a better place to answer your question. Let’s move the discussion there being that the Forum is really the right place for Tech support questions and discussion.

    I’ve created the topic here:

    Just register real fast and let’s continue the conversation and fix the issue!

  19. Mark

    October 31, 2007 at 8:12 am

    I followed the link above to the forum. For some strange reason, the tab “Buffer Overflow Protection” does not exist in the console. All of the other tabs are there except that one. I tried to register on the forum website, but I couldn’t log in after registering. I will try again later to see if my information has gone through.

  20. Ashish

    November 4, 2007 at 11:52 pm

    Thank you for posting this fix! This did the trick for me.

    I also used this opportunity to clear out the Outlook Auto Complete cache (Documents and Settings\username\Application Data\Microsoft\Outlook\Outlook.nk2). While this will be a pain in the short term as I build it back up, things are very responsive again and like many others I’m not ready to chuck things out the window!

    I’m not sure why this started happening all of a sudden (within the last week or so) when I’ve had Outlook 2007 running for months. Perhaps our IT organization pushed out something with McAfee that impacted this??

  21. MrGroove

    November 6, 2007 at 11:26 pm

    Welcome to the site Ashish!

    Sounds odd but I think your right. Your IT guys must have pushed out something. You should give them the link so they can adjust the policy (if it makes sense for your org.).

  22. Matt

    November 15, 2007 at 12:40 pm

    This is in no way a fix.. This is disabling a vital part of McAfee protection. I dont know about you all but I would rather wait for a update from McAfee than turn off my buffer overflow protection and more than likely have your computer be fully compromised by the many zero day exploits/worms/viruses floating around in the form of emails making thier way to your outlook inbox.

    You might as well unistall McAfee because most viruses come from email especailly outlook which has many security holes….

  23. Matt

    November 15, 2007 at 12:42 pm

    and I have no problem with my auto complete, VSE 8.5 here….

  24. MrGroove

    November 17, 2007 at 12:56 pm

    Welcome to the site Matt and thanks for the comments.

    I agree, that by disabling buffer overflow protection in outlook you are opening up an attack surface for your computer. That being said, I don’t agree that this change to the AV client introduces an unacceptable level of risk for the average user or corporation.
    The primary method which malicious emails infect the desktop are through attachments and malformed/malicious HTML. With this in mind, there are several ways which Outlook protects you from these threats such as Disallowing Programmatic Access, Disable of attachment preview and my Favorite, the option to convert all email to Plain Text prior to displaying it to the user. That being said, each user/company will need to make their own decision based on benefit vs. risk and the level of risk they are willing to accept. For me personally, I see this as very low risk (otherwise I would not have recommended it to my users).

  25. Robert

    December 5, 2007 at 11:57 am

    You rock! Worked for me and the complaints can now cease! Amen, Brother!!

  26. Hai

    December 5, 2007 at 2:34 pm

    I have the same problem with NK2 file on Vista machine, but i have McAfee Total Protection for Small Business. I can’t seem to locate the buffer protection. Can anyone help? Thanks!

  27. Michael

    January 17, 2008 at 5:34 am


  28. MrGroove

    January 18, 2008 at 9:09 am

    Welcome to the site Michael Glad to see it helped you out.

  29. MrGroove

    January 18, 2008 at 9:10 am

    @Hai – Welcome to the site!
    If the article does not work for you and you need more assistance, please post your problem or question in the forum so we can help ya out.


  30. Gene

    January 18, 2008 at 2:42 pm

    Thanks for sharing. Put up with two frustrating weeks of emailing with 2007 prior to finding this fix.


  31. Richard

    January 24, 2008 at 4:32 pm

    I dunno how you ever figured this out, but you managed to stave off a major problem for us.

    I was running into the issue and thought it was just my PC, until one of the executives called in to mention he was having the exact same problem.

    We are beginning to roll out Office 2007 and I was able to catch this issue and have the exception added to our EPO server before this caused big problems across our enterprise

  32. MrGroove

    January 25, 2008 at 6:50 pm

    Hi Richard and WELCOME to the site. I’m glad the article helped out your company. My CORP was going through the same issue until I figured out the problem. I’m glad it helped you out! If you have any other problems or questions, please feel free to post in our forums.

  33. Martin

    February 1, 2008 at 7:51 am

    Bow to Mr. Groove he is truly a saviour!

  34. Mirko

    February 5, 2008 at 8:35 am

    I had to push this through EPO. 3 minutes later : problem fixed.
    Thanks for keep posting solutions !

  35. Martin

    February 20, 2008 at 4:08 am

    I just changed the settings for a customer but so far I haven’t seen a result. They’re not running MacAfee Enterprise though but a smaller solution so it might either not work or take longer for the update to propagate to the clients.

    Still, huge thanks for this information. :)

  36. Victor

    March 20, 2008 at 6:06 am

    Thanks a million!!! Your solution worked wonder!

  37. georgi55

    July 1, 2008 at 8:41 am

    I LOVE this, thanks! Applied this settings to default ePO and now it’s fixed for all my users!

  38. Simon

    July 2, 2008 at 2:42 am

    This worked immediately. Fantastic. Just one question; how on earth did you think of this?


  39. MrGroove

    September 17, 2008 at 12:11 pm

    @Simon – Trial and error :)

  40. Reboots DaMachina

    September 24, 2008 at 6:56 pm

    This is more like a McAfee problem than an Outlook 2007 problem. You should change the subject to Outlook 2007/McAfee slowness problem or similar!

  41. Kamaru

    June 7, 2011 at 11:56 pm


    In my case, I have seen buffer overflow protection is disabled because I have HIP installed in it, In this case how can we proceed as I don’t see any exclution list in HIP

  42. Liridon

    May 31, 2012 at 7:44 am

    Thanks a Lot.

  43. jina.gershon

    June 6, 2012 at 1:03 pm

    You may use professional recovery software

    application effectively helps you to restore .pst file of any version of MS Outlook, beginning with MS Outlook 97

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