Alright, so I was editing a scenario in Sapien. I was placing AI in the map and creating some encounters. Everything was fine untill I added an elite commander with an energy sword and gave him a spawn point. I saved the sceneario and then closed sapien. I then reopened sapien and selected my senario. it would stay open for a second (long enough for me to see the elite had spawned), and then crashed.

How can I fix this?

For some odd reason I don't have a debug.txt

Yes, other maps open up just fine.

Just open up the scenario in guerrilla, scroll down to "encounters" in each encounters "squad" set all of the actor types to none. Save it then reopen it. Spawn each actor one t a time (don't save it after spawning them) then find the one that crashes the game and delete it. After that it should all be good. (Only thing I can think of immediately, with the description you gave)

BTW to get a debug.txt. Right click on sapien, open properties. Make it run as admin (I'm not on the pc right now, so I can't go through all the horny details) do that with guerrilla and tool aswell. Or right click each time you use it and to run as administrator.

Or click on a button "compatibility files" in your halo ce directory.