I'll address what I've seen with Xan's issues: I think that the guards abandon you and run off if they're invincible and near death. For your version, they could get easily hurt, so that might have explained why all those Johnny's ran out of your car :p I'm raising the health even more now, so that you don't get all these runaways so quickly. Also I found that after they run away and you try to discard, THAT is when you get game crashes. I'll see if I can fix that crash.
behzad_sol: the guards will only do driveby's if you equip them with a pistol, MP5, grenade, or molotov. As I said in my other post I'm going to see if I can give them secondary weapons without them always choosing it.
As for the spawning over 15 guards - that is not something I can reproduce. It may be your computer, I'm not sure. If all you're doing is spawning 15 guars right off the bat and it crashes, that doesn't happen for me. Same with discarding over 8 guards - it might have been another issue.