Hey,
So I've been in a weird trouble recently with the N900's alarms, it started after installing Qtlockscreen so I uninstalled it, but it seems that it didn't do any good.
Problem: Once the clock hits the right time, the alarm goes out, the dialog box with the big time written on it and thw snooze and stop buttons appear, alarm sound starts BUT it stops after ~30 secs, leaving the dialog box there.