Oversize desktop

I think this is an OS problem but we'll see what the consensus is. It's a little hard to describe accurately. I reformatted my HDD recently and first noticed this anomaly when I engaged the "STARFIELD" screen saver in XP. If you've seen it you know that the point of origin of the "STARS" is suppose to be in the center of the screen. On my screen the point of origin is almost off the screen to the right. Also, the cursor is suppose to stop at the edges of the screen. On mine it does on 3 edges but not on the right side. I have done some experiments and it appears that I can move the cursor approximately one full screen width past the right edge. Everything else seems normal. Wallpaper and programs fit normally. I probably wouldn't care except it's very annoying to constantly lose the cursor off the right side of the screen and have to relocate it. I've already exhausted all the driver variables and also tried every adjustment on the monitor itself. Any suggestions welcome. Thanks in advance.