I do use custom club icons, and a Gender Filters for Clubs mod.
That there's an issue with a dead club leader explains the timing. Where I am in the game is right where the first generation of sims starts dying out.
Okay...
- Removed the club mods. (Tried to save without them, didn't help.)
- Went back to a slightly prior save where I'd only been getting a 533 error intermittently. The gamer club did indeed have only one(deceased) member.
- Created a new club, which removed the gamer club. Played a bit.
- Disbanded my new club. The gamer club reappeared with one living and one dead member. (Presumably they're playing Ouija.)
- Have now run the game past the point where I couldn't save before. It still saves. So maybe I've gotten around whatever hurdle was causing the 533.
Which is the most likely culprit - the custom icons or the gender filters?