I play on PC, am updated, do have mods...and purchased HSY within the past few weeks and never have tried to go to prom.
Got the prompt to go to prom over the past RT 48 hours and each time it would crash with a critical error, saying Better Build Buy was 30% of the problem. Tried submitting a BE report but it wouldn't return anything so guessing the problem isn't actually triggering something BE can work with.
This last time I decided not to change outfits ahead of time and to keep the queue open. Instead of crashing, it took me to the Neighborhood screen, with absolutely no clue what I was to do there. I clicked on Copperdale and got screens asking who to go with. My teen Sim and her date were already listed as being at the Auditorium so have no idea why this screen would come up. Why would I want to send other Sims to the prom when my Sim was already there? But it wouldn't let me do anything...not even close it. Had to keep choosing to go back to the Main Menu just to get out of that...except if I went back in, it was still at that screen. I ended up choosing the mother of the teen to travel with but that didn't work either.
I don't follow the issues with TS4 because I'm not buying packs as they come out, like I did with TS3. I hear that pretty much every pack is buggy but lawdy, I'm waiting for months before purchasing in the hope those bugs get fixed. Seems like they don't?
I've been playing since the beginning of TS1 and every game/pack since. After all of these years and SOOOOO much money, I'd just like to finally be able to play a game without the bugs and not dealing with games that are buggier than the last.