problem:  Need to reset the offline files cache for Windows 7.

solution:
• Open Registry editor (Execute Regedit from Run window)
• Traverse to the path path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Csc\Parameters 
• If Parameters key does not exist under CSC you can create a new node with that name.
• Now in the Parameters node create a new registry value with the name FormatDatabase of type REG_DWORD (i.e DWord 32-bit value)
• Set the data in this new registry value to 1.
• Close registry editor.
• Reboot the machine

The above steps can only be done from an administrator's account. We can do the above steps from command line too. For this you just need to run the below command from elevated administrator command prompt.

reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Csc\Parameters /v FormatDatabase /t REG_DWORD /d 1 /f



Source:  http://offlinefiles.blogspot.com/2010/09/delete-offline-files-cache-windows-7.html