My guess is that you need to first give your friend an evil look, and then get out your Windows disk and put it in, and do a Repair on Windows. If you're lucky, this will work.
Also, it's not regedt, it's regedit.
And third, this is a forum about setup & deployment of .NET applications, not about Windows problems. If you have more of those, I would recommend posting them here:
http://www.microsoft.com/communities/newsgroups/en-us/default.aspx?dg=microsoft.public.windowsxp.general&cat=en_US_91a15a1e-b269-4291-b6b4-dc2d504ce9ef&lang=en&cr=USGood luck. And don't ever let your friend near your keyboard again. ;-)
RobinDotNet
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