Drive passes fsck fine. "Remember" (a front end to memtest) isn't complaining about my RAM. No crash log that I can see.
I can't tell what causes the hang, but it's been happening a few times a day, even when the machine is idle with no screen savers running.
Suggestions on what to check?
I think it might be out of warranty now, since the last time I took it in to the Apple store, they caught on to the fact that I had upgraded the drive to 2TB and wagged their finger at me.
Update: Well now it won't boot at all, with nothing plugged in, or from external USB, so I guess it's "genius" time. I'm assuming it's the video card, which they replaced a year ago. Here's hoping it doesn't take them three weeks like it did last time...
Update 2: Apple has decided that this machine is a lemon, and (with only a couple months left on Applecare) they're giving me a new one for free! So that's cool. They're also letting me upgrade it by paying the difference between the price of the one they were going to give me, and the next model up, so that's cool too. The bad news is, this might take another two weeks (it goes through the online Apple store).