I've got a character that was nearing the end of the thief & DB quests--the only major quests I haven't completed. I had a perfect, issue-free 10-hour run with this character leading up to the final quests, and since then, I get frequent crashes.

No problems with 6 other characters. I've tried removing all mods and going back 20+ hours in saves, and I still get crashes. With old saves I can play for a few hours, and then I start to get the same problems.

Aside from experimenting with even older saves, does anybody know any tricks to fix corrupted files?

No fix for it that I am aware of.....

What is your save file size? Maybe a bloat issue?

Most of the saves are around 9MB. A few jumped to 12MB, but drop to around 9MB on the following save. This is for 90 hours of play.