Oh wow, I figured out why it has been crashing. 64 is the MAX player slot, and that is what I have, but I also run STV.
Reason why it didn't crash of first map load is because STV wasn't allowed to enter, until map change, it appears, causing player slot to 65. I just ran it at 63 slot +1 STV and it worked fine.
If you used my launch options, you would of had the same error since that is where I specify my maxplayers.
Ahh... wasted hours and re-downloading stuff because of an invalid player slot. Well good thing is, CSSDM works fine