I had to purchase a new computer with windows 7 and find that I can't get my G4 program to load. It comes up with an error message that says I need a 64 bit version of the program???
As of this writing, all versions of RealFlight are 32-bit applications. No 64-bit version exists. RealFlight will happily run on a 64-bit OS, though. Many, many people (including us!) use it that way.
I'm not sure what is causing the error message you're seeing. I've never heard of that happening for anybody else. It's definitely not expected behavior.
Tech support is very good at walking people through these kinds of problems. I recommend contacting them.