I've been playing the campaign Halo 2 PC, and my game crashes after the cutscene at the end of the mission Quarantine Zone. I'm given a dmp file after the game crashes.
Check to make sure that you have all the campaign maps in your Halo 2 install maps folder. You could be missing a level or have a corrupted/uncompressed map file and it's causing your crash.
I have encountered exactly similar problem, and it is still persisting after uninstalling, re-downloading and re-installing the game. The map file is in the folder too, not sure how to see if it is corrupted.