Display defects @ windows login screen and Farcry!

Okay, when I start up windows XP Home, after the splash screen it auto-logs in but it still shows the blue screen with the blue bars at the top and bottom, which is normal. The Problem is, the bottom bar is not blue, it is a dark green and sometimes has a diagonal like through it splitting it into green and white. Similarly, when I start up Farcry, the very first Ubisoft screen that shows up is split from the top-left corner to the bottom right corner with a diagonal line. On the bottom left, the loading sequence is normal, but the upper right is black, or some other color. This continues and I have to restart my computer, because restarting the game doesn't help at all. Also, I have had the same problem with Farcry with a slight variation. Yesterday, there were just there 1-2 inch horizontal bars flashing on and off and as before, I had to restart my computer, but even then it doesn't seem to guarentee that the game will work and that the windows log-in screen will be flawless. I'm wondering if this could be a graphics card over-heating issue? Any kind of suggestion would be GREATLY appreciated. I have all ot the newest drivers, so I'm not really sure what else to do?

Dell Dimensions 4700
P4 520 2.8 GHz w/H.T.
512 mb DDR2 (2x256) PC 3200
40 GB SATA HDD
ATI Radeon X700 Pro
12x dual layer DVD +/- RW

 

Forgot to mention that I am using a Samsung 912n 19" LCD display, and there is no DVI, only analog.