ATI Radeon 64MB DDR, is it the card or the monitor?

[CJB]

I have a Radeon 64MB DDR VIVO, an Envision 19in monitor, and Win2k. The problem goes like this: Whenever I open any window with the desktop in view, the edges of the screen expand or as I put it bubble. Any clue as to what it could be, the monitor or video card?