Hi, I've got an iMac I bought within the past month. I've recently installed 10.4.10, and although I can't confirm this issue began at the same time, it seems it might have... When the computer is doing "silent" operations, like browsing regular websites, editing documents, for more than 25 seconds, it sounds like it "sleeps" the audio card. There's a "pop" from the speakers. When I go to use something with sound again, even just changing the volume level and getting the little "clicks" that go with the keyboard buttons, it begins with another loud pop, like the sound card coming back on. 25 seconds later, "pop", and it's off again. There is no noticeable hissing or humming in either state, so it's not entirely clear if the card is actually turning on and off. This problem is particularly noticeable since I have a set of highly amplified home theater speakers attached to my iMac. When using headphones, it is virtually imperceptible (although, if you look at your watch after changing the volume level, 25 seconds later, there is a tiny blip in the background). Anyone else experienced this? Any confirmation if it's connected to the 10.4.10 update?