"Worse" is an understatement! Several of the "per-scripted" Sims are actually missing the wants/fears they "have" to have in order to make the "pre-scripted" events make sense or even take place!
Examples: Cassandra's only want is to go on a date & she has NO wants/fears involiving marrying Don or talking to Darren. Daniel Pleasant has no want to WooHoo with Kaylynn OR fear of getting caught cheating by Mary-Sue. Loki Beaker has "swapped" fears/aspiration levels with Nervous Subject, and is in almost continual Aspiration Failure because of seeing cockroaches. (Actually, I have a soft spot for poor Nervous & rather enjoyed seeing him laugh at Loki for a change, but Loki is almost unplayable this way! )
I did find this advise which I might try to see what happens.
http://www.insimenator.net/showthread.php?t=42619
I am also considering doing an un-install, re-installing up to Pets (which was working fine for me) , playing through what "pre-scripted" crap I feel like, then adding Seasons/Celebrations to the mix. The lack of public outcry over this glitch really makes me think it's only rampant with the "pre-scripted" events (which most people have played through before installing Seaons) so if they are already triggered I'm hoping that will fix things!
-ZW