Nothing too complex, but it might have run out of memory. Last time it was Opera running for ~ 3 hours, a ~500kb pdf in qpdf2, a console running ssh into another machine, possibly (never got arround to checking it was running) mysqld in the background. I'm pretty sure there was a fourth app open, but nothing too different from the default apps included. I'd just installed kaddressbook and korgaizer 1.9.6 too. Also running a wireless network card (Origo card, no WEP at the time)
But it's crashed without any of those apps (apart from qpdf2 and opera) installed, and none of them, IIRC, running.
I may (may) have clicked shutdown, but that's not guarenteed.
Last time I also changed the default user name, but not UID, from zaurus to "iso" (my normal log in name - makes using ssh easier) by editing /etc/passwd and /etc/group. The SD slot has a 128MB SD card in it (it's crashed without that first time though), formatted as ext2.
I cant see any common link betwwen the crashes, so I'm suspecting a hardware problem, maybe even heat related.
I'll download the "unstable" rom tonight and play with it on my commute tomorrow.
Before the last-but-one crash (two crashes in a week, but I've been stressing it a lot harder then normal) I had a vncviewer program installed, couldn't seem to find an ipk for it this weekend (only one I found was keypebble, which was a dead link anyway)