Well, A)
@> Control Timer: Stop
B) Are you using a script? It's been a long time since I used XP, but I seem to recall the timer just being a gigantic ugly number in the right hand corner. It doesn't have a little image placed under it and it's not in the centre of the screen. So, if it is a script and the Stop command doesn't make it go away, then it might just be a problem with the script. If you made the image with a Show Picture command, then an Erase Picture command would work.