We ran into a problem recently where users on a Windows 2008 R2 terminal server would lose their connection to SMB shares.  Fully-qualified domain names do not get disconnected.

There is a Hotfix from available from Microsoft that fixes this problem:  http://support.microsoft.com/kb/2194664.  The Hotfix is integrated into into Windows 2008 R2 SP1 and the next Windows 7 service pack.