I can't speak about this, but it looks similar to what started happening to me in FFXI (except it did it to my whole screen). FFXI had worked fine for me for over a year, I had a built in crappy graphics card and it just started dying one day and doing that to me regularly. Once I upgraded and got more RAM it fixed itself. I'm going to go with graphics card might be dying or drivers as most likely, I dont think it would be the game itself so reinstalling probably wont change anything.