As network support providers, we frequently come across come across scenarios where a computer on a business domain has a user profile that has old Offline File Cache data in it. Typically, the user account has moved to a new domain, or is pointing to an old server path, no longer in use. This can happen if the user account has redirected folders enabled on the My Documents or Desktop folders – and the server is no longer in use, or unreachable. This can result in low disk space, or in many cases, duplicate files.

You also may need to delete your offline file cache if you are receiving the error message : “Unable to merge offline changes on \\server_name\share_name. The parameter is incorrect.” in your sync center.

Fortunately, the fix is relatively simple.

Windows 7

Open an elevated command prompt (Start -> type CMD in search box -> Right Click, Run as Administrator)

type : “REG ADD “HKLM\System\CurrentControlSet\Services\CSC\Parameters” /v FormatDatabase /t REG_DWORD /d 1 /f”

Reboot computer – the Client Side Cache will be cleared on your next login.

THIS WILL DELETE ALL CACHED OFFLINE FILES – DATA WILL NOT BE RECOVERABLE, ENSURE YOU HAVE BACKUPS IN PLACE.

Microsoft’s Notes :

Make sure that files are synchronized before you add this registry entry. Otherwise, unsynchronized changes will be lost.
The actual value of the new registry key is ignored.
This registry change requires a restart. When the computer is restarting, the shell will re-initialize the CSC cache, and then delete the registry key if the registry entry exists.

Windoes 7 Reference : http://support.microsoft.com/kb/942974

If you have Windows XP, follow this procedure : http://support.microsoft.com/kb/230738