Here’s the scenario. You have a dual boot machine, Ubuntu on one side, Windows on the other. You’re tooling around, doing your thing and then one day you boot into Windows and get this:
"Windows could not start because the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM."
That’s a bummer because it generally means you’ve got a corrupt registry. Thankfully most windows XP installs (unless you’ve manually tweaked it not to) create restore points for you registry from which you can attempt to resurrect your Windows install.
Hop on in to your Ubuntu install, and lets install a few tools we’ll need to access your Windows partition. You may have ntfs-3g installed already. Open up a CLI (Applications-> Accessories-> Terminal) and type: