well, I answered my own question.
It seems NSM 3.3 is to blame (sadly!). If this mod is installed, as soon as I reach 40 below the water, hell brakes loose, everything get damaged.
I will try nsm 4 to see if the problem persists.
BTW, with crashdive I go totally submerged in less than 10 seconds. wth?? I know germans were very efficient, but not THAT
