Okay so i've had osme problems with my Units main mission file that I use. I normally copy all the files except the mission.sqm and then use them in each new mission file. Now for some reason these files keep making my game freeze while on the loading screen AFTER I press preview in the bottom right. These are the mods I have:

ACE
Communiy base addons
3CB: BAF Vehicles v4.0
3CB: BAF Equipment v1.1
3CB: BAF Weapons v1.1
3CB BAF Units
TRYK'S Multi-Play Unifrom's pack
ShackTac User interface
CAF Aggressors v1.5
Task Force Radio
Blastcore: Phoenix 2
Blastcore Tracers A3

I have tried making laoding a mission that i create and then run which seems to work. If you need anymore infomation, don't hesitate to ask.