Sounds like a screen res problem to me. what screen resoloution are you using? I think (but not sure) PPrune is desgined for a minimum of 800x600 - if your using at something less then you will alwayts have to scroll left to right as well as up and down. Change to 800X600 (if you can and don't black out the screen - press F8 while rebooting to bring your machine up in safe mode if the screen goes black and have to reboot) and the problem should go away. If not, let me know and I'll scratch my already balding head again.
Cheers.