Well this crazy bug is around since CMSF. As far as I know it occurs only in Tcp/IP and only for the guest side. Soldiers that start loaded on trucks/apcs lose all/some of their weapons. Eg you are on setup phase and you load a squad on a truck. Once you press go and you disembark that squad chances are that their rifles/smgs will disappear! Please note this is not a graphics bug, the weapons disappear for good, your men will have to fight bare handed.