Our workstations (Windows 7 machines) connect to users' home folders on the domain's File Server (Windows Server 2008 standard), using a UNC path like \\server\users$\...
This has worked fine for a long time. Now all of a sudden several computers, but not all, can't access it. It says the user doesn't have permission. Using a path with a fully qualified domain name like \\server.domain.org\users$ DOES work, as does with the IP such as \\10.7.1.2\users$.
Nothing would have changed on the workstation's end, but wiping it clean by re-imaging fixes the problem. I'm not convinced the problem is on the workstation's end. I've tried everything obvious like disabling the Windows Firewall, rejoining the domain, removing antivirus, and also tried some registry tweaks I've seen suggested online.
It turns out the problem was corrupted offline files cache. So accessing the share with a different path uses a different offline files cache, one that's not corrupted.
Re-initializing the cache with the instructions found here (http://support.microsoft.com/kb/230738) fixed the problem.