The simple answer is to delete Extend.dat files from the 'documents and settings' folders.
Extend.dat is a 'performance' enhancement used by Outlook to load add-ons without the need of looking into the registry for loading instructions. When Outlook is open and you installed the McAfee Outlook Addon, Scanotlk.dll could not be cleared from Extend.dat. Now, every time Outlook loads it is using the cached information in Extend.dat to load a now missing Scanotlk.dll file -- thus the error message.
The good news is that the Extend.dat file is completely rebuilt if it is deleted. When Outlook is run the next time, it rebuilds Extend.dat using the settings in the registry to repopulate the correct information.
This needs to be done while Outlook is closed. I would suggest doing this from a login script, which should happen before Outlook is running.
del "%Userprofile%\Local Settings\Application Data\Microsoft\Outlook\Extend.dat"
As an administrator I use this:
del /f /s /q "%SystemDrive%\Documents and Settings\Extend.Dat"
You may need to alter this for Vista systems.
Hope this helps.
Ron Metzger
