My N900 (CSSU latest, power kernel) occasional freezes. It is when I am doing something with an application - no further info on more useful patterns of use that causes this yet as it's only happened a few times so far. Enough times to be worrying, though.

When it does freeze, short press of the power button does nothing. I can still blank and unblank the screen though with the side button, but that is all.

Long press of the power button and reboot seems the only thing to do. Where can I start looking to diagnose this? Logs?