You try to install a Vmware Server 2, and get an error claiming that software restriction policies prohibit this installation.

In the eventvwr (application log) you find an entry like this :

The installation of C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\1\{AF08C71F-F822-4416-87A9-2BBF5A8A5F12}~setup\VMware Server.msi is not permitted due to an error in software restriction policy processing. The object cannot be trusted.

Solution : KB9253326

http://support.microsoft.com/kb/925336