It might be power related (more likely a faulty voltage regulator). Has this happened while your PSV was running off of the battery or while plugged in? Your GPU will usually be the first one to go out in case of insuficient power. (generally speaking) The driver will detect the GPU was reset and will throw that error.
I would try a factory reset if you haven't done it yet, just to rule out any possible software problems. If that doesn't work then you will have to ship it to them.
yeah play with mine plugged in sometimes
Hmm.. Yea this is something I don't do simply because I have killed laptops by keeping them plugged in and gaming on them, it has caused motherboards to sometimes short. So I have learned to not keep things plugged in while in use.
More people say they are experiencing this problem with more than just CoD at least here in this thread, so it is kind of worrying me now, you actually might be better off replacing it. As much as I hate to now tell you this, but it seems like a safer bet seeing these other comments recently.
Have you tried rebuidling the data base or all those other options in reset and are still experiencing it? Also have you ever experienced this crash in single player at all?
If it were me before coming to the conclusing which I think you might be coming to, I would really just take a day to test all the games you have and modes and see if this problem does occur anywhere else with pro-longed use.
Pretty much what I do with PC's before I sell them to people, I gotta test them for at least 24 hours straight to see if there are really any problems with it.
I would not suggest leaving your Vita plugged in that long but it might be worth trying to do somewhat the same thing to see why this problem is occuring and if it is directly just an issue with CoD or not.