After much experimentation, I have reached many conclusions about using SCMDraft, some based on suggestions by others, others based on just what I've noticed. After you read the first few of these, you might want to just use X-tra or something. But if you do need to use scmdraft, these I think are some good tips:
-Always use "Save As". Yes, if you're a save-hog, this is a pain in the ass, but honestly, the "quicksave" feature basically doesn't work, and will in all likelihood, even if it doesn't crash the program, partially corrupt the map file.
-Disable sound. Do this by going to "Options" and then the second to last item. Yes, hearing things explode as you delete them is cool. However, I have not had scmdraft give me a "something bad happened" upon opening a map since disabling this feature.
-Turn off auto-save. Go to "Options" then "Profile Settings..." then under "Global Settings" uncheck the box next to "Enable Autosave". Maybe you use this feature, if so, don't. But, if you have any sound files embedded in the map itself, every time it autosaves you're looking at a multiple megabyte file that you'll probably never have to use (especially if you follow the other tips here). Also, it's really annoying when it happens while you're busy in the middle of triggering.
-If you have been using autosave, then make sure you go to your program files, check SCMDraft, and look at the backup file. There's a chance it might be VERY big. If it's over a hundred mbs., delete it.
I originally thought that the problems I was having were related to the size of the file or using unusual units like disruptor webs, but after doing the above three things, I have had almost no problems with staredit crashing regardless of filesize.
-If you DO get a partially corrupted file, open the map in staredit and then save as. Because of this, you'll probably want to disable the "place buildings/units/doodads anywhere" features in the options menu toward the beginning of your map so that you don't get hundreds of "could not put unit there" errors in staredit. It's always a good practice to keep things as close to staredit's style toward the beginning of your map in case you need to open it in a different editor, in my opinion.
Hope this post helps!