It turns out the problem has magically cleared itself up. I'm not 100% trusting of it yet though.
After running memtest (unsuccesfully), hdtune, and prime95, I came up with these results:
-Absolutely no memory faults (weird, right?)
-Spin-up HDD problems detected by hdtune.
Prime95 actually crashed my computer twice.
I guess I might be able to make it until December with this thing!
Thanks for the suggestions Apache!