Its been proven and the bug that caused it has been eradicated.
Now I found a pretty stupid bug:
1. select a contact
2. click on the profile pic to make it show in the middle of the screen in bigger size
3. hold your finger (menu should pop up, so you can save it)
4. choose "view picture"...
5. be stuck like in a website - and no way back - restart BBM. Great.