Sudden Short Freezes - Occasionally Happens While Playing Game

It started yesterday: in an online game, after a couple of games I suddenly got some short freezes (half a sec, never longer) in which the sound goes like a machine gun, if you understand me. This was the first instance and since then it occasionally happens in that game. Nothing weird with that, just lag. That's what I thought. But today I started an offline-only game that has always worked perfectly (in fact, it's an old game, so very low system specs), and I got the same issue!

So, it seems I have a freeze issue suddenly, only appearing in games (haven't experienced freezes anywhere else). Note that it isn't exactly a freeze. Say I move my mouse and the freeze issue happens (still moving my mouse, but the arrow doesn't move), after the freeze my mouse arrow teleports to the spot it would've been in if the game hadn't frozen for that instant. In an actual freeze it wouldn't record where I'd move my mouse, would it?

Specs:
Windows 7 64-bit Ultimate, fully updated
AMD Athlon 64 X2 Dual Core Processor 6000+ 3.01 GHz 4GB RAM
Videocard: AMD Radeon HD 6670, fully updated

While I was writing this, I noticed the PC showed a problem. I let it do its thing, and it reports a video hardware error. I DO NOT know if this is related to the problem, but regardless, I've attached the 3 files (in a zip) Windows showed me, in case it's relevant.