as I said man... this is a game crash...
After the game crashes, it messes up your graphic card because it closes suddenly and cut it all in the half... your video card is the "victim" ^^
try using your gfx card in someone else's computer... u will see your card is fine
reinstall the game, then tell what happens! also dowloadr the NEWEST client , dont try installing the old one because t will give u some bugs