Now it's working. I swear, the only difference is that I started the main application right-clicking in the systray icon instead of using the shortcut. I can't believe it. I swear I didn't touch anything else.
What happens if you create a new shortcut for pvrx2, does it work then. Or start pvrx2 from the explorer.
I remember that I had trouble sometime ago with shortcuts that were not installed by the gbpvr-install but made by me. After a gbpvr-udate they wouldn't work anymore.
Edit: Whurlston might have a better point, since you are using Vista.