Yes, I've seen this problem on my 5455 a couple of times. It is easy to fix. Turn off the Ipaq, take out the battery, put the battery back in, and turn back on. (Just take the battery out a second, not long enough for a hard reset.) This has fixed the problem on mine every time.
I don't know why it does it, and I don't know why a soft reset doesn't fix it. I do know that taking the battery out fixes it.
Hope this helps.