Is this just on G4's? I manage over 60 macs (Intel G5's) here where I work and have run all the latest updates (security, quicktime, etc...) with no problems while having stuffit loaded as well?
I'll keep an eye out for anything I see.
The only issues I've been having recently are students trying to load corrupt fonts here and there and it's crashing Illustrator!
Silly students! 