Well, assuming (1) you downloaded your copy from Microsoft, (2) we're talking about the same version (6.1.7100), (3) all of your important system files (f.e. \windows\system32\cmd.exe) show the date 04/22/2009, and the problem remains, I would download the RC again and reinstall it again, reformatting the whole drive in the process. If one of the points isn't the case, I would do just the same thing.
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