I'm not able to access Prefetch anymore. Clicking on the execution file in the Prefetch folder in Windows (windows-xp-prefetch-clean-and-control.exe), I get the cryptic message "Windows cannot access the specified device, path or file. You may not have the appropriate permissions to access the item."
I've checked with the registry and it seems OK (The Data column value is 2), I've tried using Last Known Good Configuration and several different restore points in System Restore, all to no avail. Any other suggestions, please?