This is a hypothesis but perhaps these crashers may be coming from the new collision detection code. You can revert to the old collision detection code by enabling a flag in the Troubleshooting tab in the launcher. Toggle that and see if you're getting the same issues.
This seemed to work for me. m6 crashed for me 3 out of 4 times, usually when 3rd Basestar appeared or Frigate was blown up. It did not crash one time however with default settings, so I'll replay it a few more times later just to confirm that this fixed the issue for me.
Specs:
Win XP SP3 32 bit
2 Gigs Ram
NVidia GTX 550 TI with 1 Gig Ram
Intel Core 2 Q660
Other than that, congrats on a great development! I really enjoyed it.