my PC screen turns black while in-game. it sterted doing this while playing Crysis 3 (not on ultra, but lowest graphics options), but it also doing this on much older games like Warcraft 3 and Battle for Middle Earth. my PC is a bit old. it has an AMD Phenom 9650 quad-core at 2.3 GHz, an ATI Radeon 6570 1GB and 4 GB Ram. what must i do to solve this problem?