I am running a 6 Y.O. desktop and just recently when I try to play Warcraft 3 the game will initiate and menus load but after a while, the screen just switches to grey diagonal lines running across it. I can make it go away by pressing alt-tab and then going back to the game, but it continues to reappear. I updated the graphics drivers my my Geforce 7900 GT card but it still does this. Any help would be much appreciated.