Crashing when taken off charge whilst alarm sounding

So I really like my curve 9360, it's been great, apart from this one irritating problem. I go to bed, put it on charge, set the alarm, turn it off. I then wake up to the alarm.

If I turn the alarm off and then take the phone off charge, all is fine.

If I take the phone off charge (and I've done this a few times accidentally) the phone crashes. Screen goes completely black, and everything is unresponsive. I have to take the battery out and put it back in to get it going again.

The alarm is set to music from my media card, and I've had this problem for a while (I deleted all the music from the media card, and then put it all back in, and that seemed to fix it for a while). It also does this with different songs, so it's not just a corrupted file or something like that (I think).

Really appreciate any help, thanks.