The Offline Files cache is a folder structure located in the %SystemRoot%\CSC folder, which is hidden by default. The CSC folder, and any files and subfolders it contains, should not be modified directly; doing so can result in data loss and a complete breakdown of Offline Files functionality.
If you suspect corruption in the database, then the files should be deleted using the Offline Files viewer. After the files are deleted out of the Offline Files viewer, a synchronization of files may then be forced using Synchronization Manager. If the cache still does not appear to function correctly, an Offline Files reset can be performed using the following procedure:
1. In Folder Options, on the Offline Files tab, press CTRL+SHIFT, and then click Delete Files. The following message appears:
The Offline Files cache on the local computer will be re-initialized. Any changes that have not been synchronized with computers on the network will be lost. Any files or folders made available offline will no longer be available offline. A computer restart is required.
Do you wish to re-initialize the cache?
2. Click Yes two times to restart the computer.
Then you will have to open my computer and right click on the folder you want to offline and say make Offline as it will loose all offline folders.
Method 2 Use Registry Editor
If you cannot access the Offline Files tab, use this method to reinitialize the Offline Files (CSC) cache on the system by modifying the registry. Use this method also to reinitialize the offline files database/client-side cache on multiple systems. Add the following registry subkey: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\NetCache
Key Name: FormatDatabase
Key Type: DWORD
Key Value: 1
Note The actual value of the registry key is ignored. This registry change requires a restart. When the computer is restarting, the shell will reinitialize the CSC cache, and then delete the registry key if the registry entry exists.
Warning All cache files are deleted and unsynchronized data is lost.
You can also automate the process of setting this registry value by using the Reg.exe command line editor. To do this, type the following command in the Reg.exe window:
REG.EXE. REG ADD "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\NetCache" /v FormatDatabase /t REG_DWORD /d 1 /f
Note For specific steps to re-initialize the offline files cache and database in Windows Vista, click the following article number to view the article in the Microsoft Knowledge Base: 942974
On a Windows Vista-based client computer, you can still access offline files even though the file server is removed from the network