monitor or graphics card problem??

im having a weird issue with my monitor, it just started happening last night out of nowhere. all of the sudden, the screen just..lost horizontal sync i guess?? it looks basically like it would if i were really really drunk.

the distortion isnt always over 100% of the screen depending on the refresh rate, i lowered it to try to fix it and it worked..for a few minutes and then it just appeard again starting in the middle and expanding vertically at a fairly slow rate, till it stops when it takes up about 3/4 of the screen leaving 2 "normal" strips at the top and bottom of the screen, the distorted area also looks like its being squeezed from the sides toward the middle of the screen slightly.

if i turn the monitor off, and then back on its all clear again for a varying amount of time, from 30 seconds to about 20 mins. now this is where i get really confused.....i tried using the monitor at lower res's and refresh rates and its still there(also checked gpu temp during distortion its at 58 very cool)......exceptt...when i play a game, for example... while the distortion was present on the screen, i started counterstrike cz(OPENGL) which i run at 800x600 100hz(monitor can do 140hz@800x600) it starts and the screen is clear, and i played it for about 2 hours with nothing strange at all happening....as soon as i quit and get back to desktop, theres the distortion just where it was before, same size(3/4 of the screen)???? i would think that this could rule out 1. interference, and 2, the monitor or am i missing something here? anyway id like some opinions on what u think it could be, before i go replacing anything. thanks a lot for any help in advance

specs: k7n2 mb xp2400 512mb
winxp pro sp2

bfg geforce 6800gtoc
19" samsung syncmaster 950p(about 5 years old)