Windows 7 says "Access denied" when trying to open a mapped network drive. The permissions are setup correctly. When you logout and login again (don't reboot), it's possible to access the drive. I thought this is caused by a windows service started at boot time, but I've uninstalled / disabled all services that don't belong to windows and it didn't change anything.
The server is samba. It's only one drive affected. It's one user account and one machine only. There are no error messages in event log.