According to this OpenEye report, it appears that when I wear a Hazmat Suit and attempt to stand on Fire, the suit crashes trying to do something (possibly trying to put the fire out) by trying to get an invalid BlockState property from the fire (named level). This happens every time and does not occur in IC2v2. More info as requested.

No the suit crashes attempting to find out if you stay in fire or lava, since the methode i use (for fire) is ment to be for liquid, there is a close methode regarding to that that does exaclty what i want but its named a tiny bit different.
Thanks for reporting will be patched with the next patch