Try searching before posting a question. There have been about a dozen threads started on this already. Did you read the stickies at the top of the forum?
Perhaps there should be a sticky with this specific error message mentioned in the subject. If there are dozens of threads, this would seem to be a big, if annoying, problem among RR users. I'm getting this error, but I'm using the latest and greatest, though granted I'm using it under an "unsupported" OS (under WINE on Linux).
Also, perhaps the Win500 author might have some sort of automatic "Check for updates.." mechanism in the software to stop this kind of thing from happening?