I have sometimes CTDs even with the latest patch, but overall it's quite stable. I have autosaves every 10 turns, and use quicksaves often to minimize the impact of a crash.

Personally I also switched mega-events off, since my game crashes always when the Dreadlords arrive, which is quite annoying.

Please open your debug.err file in notepad, and copy/paste the contents into a post here. This will give us some technical information that can help troubleshoot your problem. The location you'll find the debug.err in varies depending on which game you're playing:

Dread Lords: My Documents\My Games\GalCiv2
Dark Avatar: My Documents\My Games\GC2DarkAvatar
Twilight of the Arnor: My Documents\My Games\GC2TwilightArnor

Older versions may store the debug directly in the location the game is installed at.

Be sure to copy the debug immediately after the error occurs; if you start the game again, the debug will be erased and recreated for the new session.