False "File in Use"
 

User accesses file on network via Windows Explorer, gets a "File in Use"
dialog indicating he already has the file open, which is false. User clears
dialog and can then immediately open the file just fine. All users on
network are experiencing with Excel files (and perhaps others).
Intermittent, but frequent issue. All users on Excel 2003 with Windows XP
Pro, servers are Windows Server 2003 Standard.