Blurry Gaming Screen...

Quinthalus

<div class="IPBDescription">All HL usage is blurry...</div> I'm using Windows XP, and apparently the only problem I'm having is that the screen becomes blurry and shifty when I try and play any part of Half-Life or its mods. It doesn't start until I start the game itself, and apparently its only graphical as when I actually enter the game I can still "see" around. I can move the mouse and see motion, but the exact specifics are lost to the snowy blurriness. Any help would be great.