Outlook ntdll.dll error with Cloudmark

Outlook crashes with ntdll.dll error with Cloudmark installed.

If you are experiencing problems with Outlook periodically crashing and the error report always seems to contain "ntdll.dll" as the cause of the error, it may be related to having "Cloudmark Safetybar" installed as your anti-spam protection.

Cloudmark Safetybar / Cloudmark SpamNet

Firstly, let's be clear:  The Cloudmark anti-spam products are the best and most effective anti-spam solutions we have ever found for the vast majority of users.

We have used Cloudmark since it was on early beta-test and recommend it to any users receiving any amount of spam.  It's centralised detection and absense of the naive "word list" detections and updated use by many vendors makes it inherently superior to other solutions.

Resolving the problem

The problem appears to relate to the folder "Microupdates" which is created by Cloudmark in the users "Application Data" (Windows XP) or "AppData" (Windows Vista) folder:

Windows XP:

C:\Users\[Profile Name]\AppData\Local\Cloudmark\MicroUpdates

Windows Vista:

C:\Documents and Settings\[Profile Name]\Local Settings\Application Data\Cloudmark\MicroUpdates

Firstly, close Outlook, if it is still running and then rename or delete the folder "MicroUpdates"

Restart Outlook and test.

If the problem persists, close Outlook and rename the parent Cloudmark folder, then copy the "SpamNet" folder and any files named cdol* to a new, replacement Cloudmark folder to keep your whitelist settings.