Oh no! Outlook crashing on ntdll.dll! Whew, problem fixed!

Posted by Dan on Aug 9, 2007 @ 8:26 AM

So I woke up this morning and Outlook had crashed on me. Every time I'd try to restart Outlook, I'd get the same crash error—even rebooting didn't help. The error was in the ntdll.dll.

I figured maybe there as something in my POP3 account that Outlook was having problems reading, so I snagged a tool to allow me to read the headers and delete messages. In my POP3 account were some messages with some Shift-J encoding—so I thought for sure that was the cause of the crash. However, even after deleting those messages I was still getting crashes.

After over an hour of troubleshooting, I was getting pretty frustrated. I figured at this point it was either some Windows Update that installed itself or a add-on causing the issue.

The primary add-on I run is Cloudmark—which is a spam filtering tool. I decided to head on over to their Community Forums to see if anyone else was having this problem. Sure enough it seems like most Cloudmark users started experiencing the problem some time last night.

After reading through several more complicated solutions, I found one that was very straightforward and worked for me--just renaming the \Documents and Settings\[Profile Name]\Local Settings\Application Data\Cloudmark. Here are the instructions from WildBill

In Vista, go to C:\Users\[Profile Name]\AppData\Local\ and rename the Cloudmark folder to Cloudmark.bad.

In XP, go to C:\Documents and Settings\[Profile Name]\Local Settings\Application Data\Cloudmark and rename the Cloudmark folder to Cloudmark.bad.

Then start up Outlook and you're good to go. You do not need to uninstall or reinstall Cloudmark.


In order to preserve your whitelist settings, you'll want to copy 2 files over from the old directory to the new directory.

  1. Close Outlook.
  2. Copy the files cdol_firstunblock.dat and cdol_whitelist.dat from your old \Cloudmark.bad\SpamNet directory to your new \Cloudmark\SpamNet directory.
  3. Restart Outlook.

Those steps worked for me. So if you're having problems getting Outlook to work and you're running the Cloudmark Spam Filter tool, try these steps to see if Outlook starts working again. It worked great for me.

Categories: Personal, Technology


  • Worked like a charm! Of course, Cloudmark has no mention of this on their support site.
  • Glad it helped someone else out. I can't claim to have come up with the solution, but I thought maybe some readers out there might be having the same issue...
  • Hey Dan,

    Your fix worked perfectly. Good show on the research, I thought I was going to have to uninstall the Symantec Antivirus add in again! ;P
  • 1) Thank you for posting this
    2) Thanks to Google for indexing this page so damn quickly!

    The same problem started for me this morning. This has fixed it. Looks like an official acknowledgement and fix is here: http://www.cloudmark.com/desktop/forum/viewtopic.p...
  • Thanks!
    Worked fine for me! (OBviously)
  • Thank you, thank you, thank you!!

    I spent hours trying to fix this problem yesterday with no luck.

    Your suggested fix did the trick and I am so happy!!

    Thank you so much!
  • Many thanks for your solutions; it worked instantly. We had spent more than 10 hours working this one out!
  • It worked like a charm. Our tech group was working all night for a solution. Thanks for posting it! :)
  • Thank you a million! We have worked on this for 2 days and unable to resolve until we read your information above. You are great!
  • I have also been working on this for 2 days and got nowhere until I found this entry. You are one smart dude! Thank you, thank you, thank you!
  • Can I mail you a blank cheque!

    Thanks for the help.
  • OMG! Thank you!
    My IT dept wanted me to backup so that they could reimage my HD on Monday (kneejerk reaction)!

    You solved my problem! Thank you very much!!!
  • This worked - after hours of running antivirus software and antispyware removal tools and so and so on; very much appreciated!
  • Oh my god I cant believe that fixed the problem. I kept getting that error report and tried everything for about 4 to 5 hours. I come in today find this blog and fixed everything. Cloudmark you can bite me.
  • I still think Cloudmark is one of the best tools for fighting spam.

    I've been using Cloudmark since it's early betas and this is the first problem I've seen like this.

    It's really a shame, because it definitely can be a huge "black eye" when it comes to word of mouth referrals.

    Hopefully they've learned their lesson and the plug-in will have better exception handling in the future.
  • A Million thanks...after 3 hours of searching / struggling I fond your fix which worked like a charm !

    Cheers !
  • Thanks a ton! I had a LinkedIn toolbar in Outlook which I removed after reading this description. All readers please try and remove any plugin you have installed in Outlook before you try any "kneejerk" reaction!!

  • I found that the crash for me was caused by upgrading to Office 2007 and outlook automatically started using a French dictionary to correct spelling. I changed the dictionary to English, not an easy task in some cases, and everything was fine.
  • I am looking for the cloudmark folder, I cant fin it inside the aplication data folder or anywhere else, But I do have an error with ntdll.dll. file on outlook when it try to send/recieve. Any Ideas...Thanks!
  • this is my error
    AppName: outlook.exe   AppVer: 12.0.4518.1014   AppStamp:4542840f
    ModName: ntdll.dll   ModVer: 5.1.2600.3520   ModStamp:498fff10
    fDebug: 0    Offset: 0000100b

    Any Ideas??
  • @Roberto:

    If you don't have the Cloudmark Outlook plug-in installed, then you'd have
    no Cloudmark folder. If you do have it installed, it's possible they changed
    the location since I posted that blog fix--but I can't confirm since I no
    longer have Cloudmark installed.

    The cause of the ntdll.dll seems to be when you have an Outlook plug-in that
    is misbehaving. Try loading Outlook up in safe mode:

    Hold down the [Ctrl] key when starting Outlook. The program displays a
    dialog box that gives you the option of starting in Safe Mode.

    That should temporarily disable all plug-ins. If that allows you into
    Outlook, then you'll need to figure out which plug-in is causing you issues.
  • In some cases, Outlook 2007 crashes immediately after clicking "Dismiss" or "Remind me later" on a typical reminder window.

    The event log says:
    Event ID 1000
    Faulting application outlook.exe, version 12.0.6665.5003, stamp 5061d307, faulting module ntdll.dll, version 5.1.2600.6055, stamp 4d00f2a2, debug? 0, fault address 0x00036ddb.

    Part of the solution was already posted in the Techguy forums by flyhon on 24-OCT-2008:

    1.. Double-click HKEY_LOCAL_MACHINE.
    2.. Double-click SOFTWARE.
    3.. Double-click Microsoft.
    4.. Double-click Windows NT.
    5.. Double-click CurrentVersion.
    6.. Double-click the Drivers32 folder.
    7.. Right-click the msacm.voxacm16 entry, and then click Rename. Change the name of that entry to no.msacm.voxacm16
    You can do that with a REG file like this:

    Windows Registry Editor Version 5.00

    [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Drivers32]
    However, in my case, it seems to be another ACM codec in addition. After disabling the vct3216.acm (Voxware Metasound) the problem initially seemed to have gone. But after switching to another Outlook profile (Exchange) the problem reappeared. For now, I have disabled all ACM codecs with the Codec Tweak Tool, and the crashes now seem to have gone. Hope that it really fixed the crashes now.

    Kind regards,

Comments for this entry have been disabled.