screen flashes colours then shuts down

Okay, so let me start off by saying that this is not the same issue that most experience. I have searched and searched and found not really anything like this, similar, but not the same. Basically, very randomly, my desktop PC screen will just start rapidly flashing colours for about 30 seconds, then the computer shuts down. There is no pattern or consistency. Sometimes happens 3 times in 1 day, then not for a week. It is not a program that I use or anything that triggers it, well I don't think, because I basically only use the same couple programs all the time, and this crash is speratic. I posted a video on youtube so I could put a link here so you can actually see it happening (it's 17 seconds, took 13 to get the camera going I guess!) I hope someone can help because I'm out of ideas at this point and really don't want to have to reformat this freaking computer! I've had to do that way to many times with the old one, then we finally got this just just December of last year I believe. Please help!!!!! thanks - cheers - Josh


https://www.youtube.com/watch?v=xNrq...94MqmSm21qmfSA