We also have a Snap Server 1100 and have compatibility issues with Windows VISTA.
The positng by Ian D references an option under Administrative Tools entitled "Local Security Policy". This option does not appear on the version of VISTA I am running. In fact, when I do a global search for "Local Security Policy" in Windows, I get no hits. Has anyone out there encountered this situation? Any suggestions on how to make VISTA talk to the Snap Server?