Vista - Games crashing!

I noticed this was happening a few weeks ago as I exited games, it would suddenly stop working and get an error "program failed" message in multiple games (oblivion and left 4 dead). In the last week, it's started to happen more and more often. Now it's closing out programs 5 minutes in to any 3d game (oblivion, fear, left 4 dead).
This is strange, as I've been using this system for months with no problems.

Tried running oblivion in a smaller window with speedfan on. Temperature peaked at 53C, and then cooled down a bit, and then computer crashed a few seconds later. Later I started up l4d on single player, paused it immediately to go to the bathroom, came back and it had crashed.

Some of these problems occurred after installing a new kodak printer. I'm noticing now that the kdiscover.exe is crashing often, although not neccessarily at the same time as my games. I uninstalled that as a test, still crashes. I also tried shutting down racagent (as that helped a friends computer). At the time it seemed to help, but the crashing continued to get worse.
I thought that drivers might be the issue, but newer drivers has not stopped the problem. I run AVG every morning, no viruses detected thus far. And the computers not running slowly. I ran defrag, and ccleaner doesn't detect any problems. Some of the other programs (registrybooster) did, but I would rather not pay $30 dollars unless I'm sure it will solve the problem.


I've attached the msinfo and dxdiag files. Any help is appreciated, as I don't want to waste ANOTHER weekend trying to fix this thing.
I run vista premium home edition, 64-bit

Processor AMD Phenom(tm) 8450 Triple-Core Processor, 2100 Mhz, 3 Core(s), 3 Logical Processor(s)
Name ATI Radeon HD 3200 Graphics

Apart from kdiscover.exe, do any of these game crashes point to a particularly consistent .exe or .dll in the error message?

Well, I system restored back two weeks and am not having trouble now. still, it was having trouble as I exited games as far back as a month ago. It was also starting to crash whenever I tried to create a restore point (before I restored, which seems weird). I'll post again if the problem returns.