Hello and welcome to Bleeping Computer.
I used to get that same error message back when I had a GeForce 6200 AGP video card. I actually went nuts trying to correct the problem.
First off before I forget to add this link that is related to your Windows 8.1 OS as it was with Windows Vista, so I am posting it here.
Again, sometimes Microsoft's solutions work for more OSes than the article states, so when you see Windows Vista listed at that link, please don't assume it won't work for Windows 8.1.
What is happening here, is your video card is taking longer than expected to refresh your current screen. The link above tells you how to edit your windows registry to change the time allowed before your Windows 8.1 OS decides to reset the video card manually. That is why you see that flash on your screen and the notice showing up at the Windows notification area near the system clock that your system was reset.
Please read what is posted at that link and ask what ever questions you need answered and I'll be glad to help you out.