Is it only during the game? If so download and upgrade the newes video card drivers. If it happens outside of the game does it happen when you are booting up the PC? If not then when you are turning it on tap the F8 key repeatedly at the Windows Advanced Options Menu choose Safe Mode. Login like you normally would. Click Yes on the box that pops up. Right click on the Desktop and hit properties > Settings > just click apply and restart the computer that will reset your video card settings.
If it happens even when turing on the PC then try using the OSD (On screen display) on your monitor to change its colour/brightness/contrast.