If you delete a cached profile from c:\users using explorer or command prompt, next time the user logs in he will always be presented with a tempoary profile. The Vista PC will not download the cached profile from the server like it should. The user will also be displayed with this error:
What causes this, Vista now tracks user profiles in the registry under:
If you accidently deleted cached profiles from c:\users simply log into the vista PC with a local administrator account and navigate to this registry key. Delete all the SIDS of user accounts whos cached profiles have been deleted from the registry. Now next time the user logs in, it will automatically download their roaming profile from the server again.
To prevent having to do this registry hack in future, please ensure you always delete profiles through User Profiles under System Properties.