In some instances, Vista installs may not have a properly working offline files folder. In this case, you may need to re-initialize the cache.

So if you find that the activate offline files is not available in control panel then you may want to apply this fix.

To fix the missing offline files in Vista you need to create the following DWORD in the registry and give it a value of 1.

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\CSC\Parameters\FormatDatabase

Note: Any edits to the reigstry are at your own risk and you should always take caution when editing the registry. You may also lose any unsynchronized changes when re-initializing the cache.