I am on an iMac running 10.6.8, using both Safari and Firebox, and using Logitech USB headphones. No sound either on the headphones or internal speakers. Upgraded Flash Player and Shockwave without helping the sound. What gives?
I don't know squat about computers, but everybody keeps saying "Make sure you don't have Flashblock turned on" or something like that. Then the other person says "Oh! That did it, thanks!". If that makes any sense to you, glad I could help. If not, sorry, I'm useless.