Due to the age, it's probably just a sign of the laptop hardware wearing out. If you want to ensure that it's getting a good air flow, get some compressed air and blow the dust out of the inside. If you can take it apart safely and clean it that way all the better.
If that fails, try uninstalling and reinstalling your graphics drivers. If that doesn't work either, your last step may be to reinstall windows as well.
It does suck when old laptops die, if they lasted until the end of time we'd use them until then.