Look for the mod "Cops back on the beat". The mod will spawn the cop cars and cops in traffic. Note: This will not make female cops appear however. Just use the popcycle.dat. Not popgroups.ymt if you have dlc cars appear in traffic. This will get rid of it.
All seems to be working fine now and I am glad this was not a car related problem as that is what I have been reading throughout these forums. It is strange how this was a pack that included only road signage and some building mods that would cause this to crash!