So this has started happening today, whenever I try to play league it does some scary stuff to my monitor tested with other games and it's only leg that does it. I have to restart computer to fix it.
Out of curiosity, what happens when you use the Print Screen button when it's doing that? Does the resulting picture look normal or does it also look messed up?
I'd probably re-install / repair League and go from there. If it's working fine with other games it's not too likely to be a hardware issue.
The only time anything like this ever happens to me is when the resolution is set incorrectly. Though I have a dual monitor setup. It's worth a shot anyway.
Improper resolution/refresh rate.
