Ever since we set up two new suites of PCs in september, we've been getting random application error messages at log off. These are occuring on every PC since we ghosted an image to the lot. This is what I've pulled from the application event log:

Application popup: Explorer.EXE - Application Error : The instruction at "0x019d1da0" referenced memory at "0x019d1da0". The memory could not be "read".

Click on OK to terminate the program
Click on CANCEL to debug the program
I've also had this which may be related:

Windows saved user NCTC\user registry while an application or service was still using the registry during log off. The memory used by the user's registry has not been freed. The registry will be unloaded when it is no longer in use.

This is often caused by services running as a user account, try configuring the services to run in either the LocalService or NetworkService account.
Any ideas how to solve this?