Normally you would get a message like;
C:\Program Files\Some Folder\Some Executable.exe is not a valid Win32 application, where "Some Folder\Some Executable.exe" is the .exe application file that failed.
Also, are you saying that your XP still works, but you cannot explore the C drive? If so, what are you using to explore the C drive?
I cannot access the C drive, get the above error message. Also, when doing a right click "OPEN" and "EXPLORE" are not written correcly, I can only see some weird characters. Could it be a virus?