General gaming lag and lock ups can be caused by a wide variety of things. First check to make sure that your computer is meeting the system requirements, as written on the side of the box for the game. Make sure that your have at least 512 Megabytes of RAM in Windows XP or 1 Gigabyte in Windows Vista. If you have a onboard video card, check my help document about no display. Follow the steps, disabling the onboard video card can free up resources. If you are seeing junk on the screen, like lines, dots, ext... it could be that your power supply is not powerful enough or is burning out. Check the section I wrote on, if it is time to replace your power supply. There is also a link on my gaming center to a power supply calculator. If it's not the power supply and your getting junk in the visual screen, it could simply be a defective video card. Contact the manufacturer for a replacement or if possible exchange it at the place of purchase.