I recently had a client who had received some new Dell computers with NVidia cards.  The users were able to get authenticated and out through their proper CFS policy settings using their SSO Group membership in the SonicWALL.  Then the users would randomly drop for a while and when we tried to troubleshoot it they would be working again.  I finally was able to get together with a user who was experiencing the problem while it was happening.  I was able to see and test through the SonicWALL tools that it was showing that the machine was using an unknown account and getting the default CFS policy instead of the less restrictive one that the particular user should be getting.  Also it was showing that the person currently logged into the machine was the local UpdatusUser service account used to run the service.  Since that local user isn’t on the domain every time it tied to run it dropped that machine down to the default policy settings.  I checked with the local IT person for the company and they said to just disable the service.  Once we did that the issue resolved and there were no more intermittent issues with CFS blocking pages that the user was supposed to be able to access.

http://forums.nvidia.com/index.php?showtopic=178965