Hm. He'd probably need admin rights to install anything anyway, so you don't want him using "Guest". You're still braver than I am, i wouldn't have anyone using my box if i weren't there next to them. But i'd say either do what deuce said, or use "litestep.exe -uninstall", or just do a search in the registry for "litestep.exe" and replace it with "explorer.exe" (i think that'll work)