Hey Deviltron, sounds like you were asking about ways to deal with a freeze-up in particular. With ice diving, freeze-up are always an issue, but proper prevention techniques are worth their weight. GM's post is particularly important in the winter.
Add these on to GM's list:
1. If you are going to be in "ice-up" conditions, make sure you have added the proper environmental/anti-freeze kit to you first stage. Also, if your second stage is plastic, it may contain metal inserts to help keep ice buildup to a minimum.
2. Keep the tank warm before the dive.
3. Spastic breathing can cause problems (fast breaths etc)
Anyone like to add more?
Just my 0.02