[ctmagnus]

Try pulling the battery for five or ten minutes and reinserting it to see if this clears it up. You shouldn't have to reinstall. Just doing a hard-reset (hold down the calendar and iTask buttons and press the soft-reset button in for five mississippis) should correct it but that's a bit of an extreme measure.

But before you do that, I'd check Outlook on the desktop to see if there's an appointment on that day (regular appt, all day or multi-day event) that may be causing the crash. It's possible that there's a particular string or strings of text somewhere in the appt that's causng the lock-up.