To CO2 issue if memory serves, usually happens if you ALT+TAB out of the game while submerged. If it does happen, do as Sailor Steve says, save and reload the game. Try to do it though, while you are surfaced. That should take care of it, if it does occur for you.
I have had to for specific reasons, ALT + TAB while submerged, and (knock on wood) haven't had it happen. Also had to save a couple times while submerged, and come back to the game later on, and had no ill effects, so it could just be a glitch from computer to computer, and not a standard issue that everyone sees.
That's not to say it won't happen in the future though.
__________________
A legislative act contrary to the Constitution is not law.
-John Marshall Chief Justice of the Supreme Court
---------------------
|