Just to confirm here, I decided to reinstall my game to try and remove the mass of errors, and I could never get it to instal within ProgramFiles correctly (x86 because I'm on 64bit, but same deal). I installed it to desktop instead (the installer will generate a new file for you if you give a non-existent directory) and it runs smooth.
Is it possible for the automatic installer to default to somewhere else? With all the trouble windows causes, it seems like making the desktop the default instal would make things easier. That, or never patch it and just do complete releases *shrug*