Just a quick note to record this link:
ScaryBear software offers (for free!!!) a couple of utilities to get rid of the recurring and annoying problems with notifications queue.
A couple of days ago I was working with my WM5-powered device, and an alarm came up. Clicking here and there and I manage to have a sort of "eternal alarm and I had no chance to remove it. Grumpf.
So I turned off the noisy phone and went googling around, and scary bear solution worked.
Be careful: they do not guarantee that their software will work on anything newer than Pocket Pc 2003; on the other hand on my windows mobile 5 phone it worked.