That happened when N900 was charging, maybe that was bq27x00 related. I use Advanced Power Monitor (and its dependencies), Qt Battery Widget (also uses same modules).
There's something strange about it, i can't repeat it, but unloading bq27x00_battery module will send phone to reboot.

Also noticed that somehow the DL speed is affected by current CPU clocking - when Opera in background, using FAM provides 100kb+ DL speed, FAM only - 100kb<. Maybe that's linked, i don't know.

Is the BFS scheduler thread-safe? Please check, maybe problems coming out from this. I sometimes saw my LED showing undefined colors for usual things.