The Forge CE beta server has been reset and StarFleet2.exe (current beta build) replaced in the validatedclientfiles folder.
SFHQ, I'd have to look at the code, but I believe the server calcs the CRC32 for each file in the validatedclientfiles folder and stores them in memory (only reads the files on disk at startup) for comparison when the client sends their file CRCs. Similarly, I believe the client reads the files from disk. The values have to pass through memory at some point of course... but if I get where you're driving, I'm reasonably sure that the client does not CRC the running image of itself in memory, but rather the copy on disk, it it does not then it should and I will make it so in SFC:CE.
But the way to test the suggestion you make (bad sector) would simply to be to do a full scandisk with surface check. However I do not believe that is necessary, as during my remote session on deadmans machine, I renamed his original exe (thus still occupying the same place on disk) and placed a copy of the backup StarFleetOP.exe (2552) from our FTP. So the bad sector theory is out. (at least a bad sector in the region(s) that StarFleetOP.exe occupies)
Keep the theories coming though... I currently have no explanation for this one other than the theory that windows XP has changed somehow.