Gadzooks, there are several things I would do (I am using Win XP Pro though). If you are somewhat savvy you can install and run Hijackthis it will give you a log of all the stuff in your resistry. If you can identify which is this malware and not anything you installed or came with your computer you can delete those keys or at least zap the one that keeps triggering your pop ups. If you are not savvy there are forums and Web sites where you can submit your Hijackthis log and they can tell you which to zap or which not to touch.
If this thing is somehow connected to a Web site apart from your computer you can install ZoneAlarm free (works very, very good for a free program) and after some configuration it will block it from running or connecting to wherever on the Web.
Have you tried Spybot to see if it can find it? Or if you are using Win XP did you pull up msconfig and try to go back to a restore point before you installed this GameVance?
Then there is CCleaner or Adware (by Grisoft) they worked well for me in finding nasty crap.
Perfect Uninstaller worked very well to get rid if junk before I got savvy enough to use Hijackthis, the down side was it cost me money (not much) for a year’s subscription.
Did you try running a search back a day before you believed this GameVance started popping up to see if there were any new file added or modified in that period? Chances are it will show and then you can delete it, especially any .exe files.
You have weapons thought you might have to use a couple as a cocktail instead of relying on just one. Good luck.