I have the similar setup NVR3216v (with 2.616 Pal firmware) and HFW4300s (with NTSC firmware) with no trouble. Maybe you should describe your problems.
If you want to go back to NTSC firmware, try google General_NVR3xxx_Eng_N_V2.610.0000.7.R.20130912(BIN). I think that's the latest/newest available NTSC firmware on the net.