Home > Uncategorized > Outlook crashes with an ntdll.dll

Outlook crashes with an ntdll.dll

Thanks to Dan for posting a fix to the Outlook crashes that many people have been experiencing. It all turned out to be Cloudmark ..here’s the fix.

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.

Categories: Uncategorized
  1. bob
    August 10, 2007 at 8:23 pm

    great fix! Thanks!!!
    Have been doing everything trying to isolate problem and just saw your post…Thanks for the great work.

  2. May 3, 2010 at 5:16 am

    Create a new profile in Mail applet in Control Panel regardless of the OS.

    1. Go to Control Panel > Mail

    2. Delete the default profile named “Outlook” or any other that you may have created yourself.

    3. Create a new profile named something other than “Outlook” like, “NewProfile”, “JohnAtHome”.

    4. Rename the PST file as well. e.g. if old PST files was “Personal Folders 1”.pst. Change it to something else like “JohnsEmails.pst”.

    5. Fire up Outlook and you shall not have a problem now.


  3. May 3, 2010 at 9:37 am

    I am not sure if I would suggested that option. You are deleting the Outlook profile and just recreating it. You will lose your NK2 file if you do so (which many rely on..even if I don’t like it). You are creating a situation with potential email loss as well. IT does work.. but I don’t recommend it.

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