Nokia :: 5800 Freezes After Hang-up

My 5800 sometimes freezes when I hang up after a call (or actually when I try to hang up). The phone freezes in the call screen and the phone is partially responsive because I get a reaction from the vibrator when I'm pressing "Hang up" (sometimes it freezes directly after answering so instead of "hang up" a have frozen "answer" screen). And another thing: I can call to my 5800 from another phone when it is frozen, I hear tones in the calling phone, but my 5800 is not notifying of this.

The only solution is to restart the phone. I've had my 5800 since v11 of the firmware through v20 (and v30?) and now the most recent v40 firmware. The problem persist and it freeze call screen has acted the same in all versions. This should have been fixed by now! Calling is a basic function of a phone (!), I wouldn't care too much if it froze when I played a third party game or something. But now it is basic functionality that doesn't work. If I have the music player and podcast application (downloading) and call comes in and then the phone freezes I would understand. But I cannot accept it when it happens to an idle phone with no open applications.