BSOD when left idle, STOP code 0x0000007A

Basically as titled. When left idle for any extended period of time (sometimes after 30 minutes, sometimes it's gone as long as about 30 hours), I come back to a BSOD, either a crucial process or thread has stopped or a kernel inpage error. Started roughly a month ago... today's the first time the dump hasn't either failed (0xC0000010) or simply hung after initializing disk. I'd appreciate any help on the issue, and thanks in advance.. I found you guys through googling the crap out of my stopcodes and I'm really impressed with the time you guys volunteer to help people out, so I definitely appreciate the hell outta you guys

Well, simply clearing out the space on the main drive has seemed to contribute greatly to the stability of the machine (before it would BSOD almost without fail if I left it alone, now it's gone a trip to work and a night's sleep while staying on) It's not really long enough to be conclusive, but I'm going to go ahead and mark this as solved. I'm having issues with the drive test (my computer's not being very friendly about booting from the boot disc to run it) but I'll get it going eventually I'm sure and that'll let me know if it's a bad drive or not. Thanks for the help, YoYo, I appreciate your time.

We-e-e-eell. So we're still getting BSODs (I'd post logs but it's still not actually logging them, just failing the dump or simply hanging after trying to initialize to dump it) and when I finally got the computer to realize I was trying to boot from the CD, the seagate tool didn't see any drives. The hell? So I'm not really sure what to do next as far as trying to check my drives for errors.

Well, I've managed to get the disk check utility to run twice now and in both cases it just has nothing to select and says no hard drives are connected, check jumpers etc etc. Exit program, ctrl-alt-del, hey look, it's windows on my driveless machine! So I'm at a loss at this point. Should I simply assume that one of the drives is failing (probably the OS drive?) and replace it, or what?

On a related note, now after restarting I'm losing settings in programs. Chrome is no longer logged in, fails to save my zoom level on pages, Trillian forgets settings like having timestamps on, Steam no longer has timestamps or uses my changed overlay hotkeys.

Upon using HDTune I've discovered the SMART health of my main drive is bad. Several errors on the disk, pointing to a failing HD as you thought. I'll be replacing the drive within a week, then I'll report back to update on whether the problems have stopped.