speaker issue

Over the years I've been using Harman Kardon Soundsticks with first a G4 and then two G5's (the current one is Intel-based) with never an issue. Last weekend assorted maintenance upgrades at the university required a brief shut-down and we were asked to turn things before before leaving. I turned everything off with the surge protectors and left. On MOnday I turned everything on but the computer no longer recognizes the Soundsticks under the sound output devices. The speakers are powered, and the USB cable when plugged into another computer has the "ding" recognition sound --- though the device (speakers) don't show up. I'm assuming it's a driver or application issue, but don't really know. If it that is the case, I also don't know where to find the current/appropriate resources -- Harman Kardon doesn't seem to provide this info. If anyone can help, I'd be very grateful.