Hi mogn,
Try changing your theme to Classic then restart TG2. Quit it and change your theme back to the one you like to use. Restart TG2. If it still isn't working then try rebooting between theme changes.
Otherwise I know that somewhere in XP, Displays control panel I think, there is a slider which lets you control how much hardware acceleration is used for drawing the UI. I would suggest that you move that slider all the way to the left and see if that fixes the problem. If it does try moving one step to the right until it stops working, than moving it one step back to the left.
Regards,
Jo