It can be heat or a driver issue. When I see this I often find that a thorough cleaning down to the heatsinks is best for older laptops. We have a note about cleaning with pictures in this forum's sticky post.

Next? Your post reveals there was a driver bug and it appears you never tasked the maker to fix it. At over 2 years that opportunity is now gone so when you have a backup of your system you could try other video driver versions or reload the OS.
Bob