Almost sounds like an IQR sharing issue, memory related problem or similar.
I would recommend you start by running memtest, the bootable ISO is the way to go, there is a version that runs in windows too though. I believe there is a version of memtest in TPU Downloads. Google about the program and you'll find a ton. Great program for sure, if your ram is underpowered, timings are too tight or something is just off enough to cause errors that could very well be donating towards your issues. As everything calls on RAM to function for the most part, it's pretty damn critical to have stable memory.
Then I would recommend you download and run Prime95 and/or Orthos Prime 2004, both stress test the CPU and can stress test the memory and nb to an extent. I would recommend running overnight in Blend mode on either to see if there is a write/verify issue, possible overheat issue or similar.
Next I would say maybe try installing updated chipset drivers, directx webupdate, sound drivers, etc.
FYI I've seen all of those BSOD messages when my first kit of DDR2 (Buffalo Firestix DDR2 800 2x1gb) went south...things would be fine for a little bit, then randomly whether it was 5 minutes or 5 hours my system would either hardlock, freeze, stutter, BSOD or randomly restart. Replaced the ram with some G.Skill stuff of similar specs and ratings, and my issue was fixed.
I've also had a PSU fail, a cap blew and leaked on my old vid card (9600GT) I was able to clean up most of the mess before damage was done, that card lasted another couple years before it hit the bucket. That was a scary time, never again would I use a $20 PSU..and I never have. It was rated for 550W, but only had like 16A on the 12v, my old P4/AGP/DDR rig destroyed it running stock!
Well check back if you decide to do the stress tests and see what we have after that. Hope that helps!