Months ago I already posted a thread about this problem; I didn't really get any responses other than advice to reset the PRAM. Since then the problem disappeared but has come back two or three weeks ago. Now I should say, resetting the PRAM always works and fixes the problem, but I can't restart my computer and reset the PRAM 50 times a day. Anyway... I have an extremely convoluted and hard-to-explain problem with audio output. Let's start with a fresh, PRAM-reset computer. I try to adjust volume (with F10/F11/F12); everything works fine. I go into sound preferences and attempt to adjust volume from there. Everything works fine. Then I plug my headphones into the audio out jack. In the next 3-4 seconds if I try to adjust volume with the F-keys, my screen shows the volume being adjusted but there is no sound output from the headphones. Then, one of two things happens. Either (1) anytime within the next 5-10 minutes if I try to adjust volume with the F-keys it shows it being adjusted but there is no sound output or (2) anytime within the next 5-10 minutes if I try to adjust volume with the F-keys there is a little ⃠ ("no" symbol) and the volume won't adjust. Now here's where the really weird part comes in. About 7 times out of 10, if I go into System Preferences and attempt to adjust volume from there, I get the little boop noises just fine. Also, adjusting balance has the intended effect (it will adjust from left to right just fine). However, the F-keys still produce one of the two aforementioned scenarios. About 3 times out of 10, the sliders in sound preferences will also be greyed out and it will say that the "selected device has no output controls" (or something along those lines). After about 5-10 minutes, my computer will usually freeze for a second, I will randomly hear the little "boop" noise out of my headphones and everything - the F-keys and the sound preferences - starts working fine. Also, random clue - this whole problem seems to affect video playback on YouTube - when I try to adjust volume (and it doesn't work) the video may freeze for a second and the whole thing glitches, but then the video goes back to normal (and there is obviously no sound output). I get a very similar situation when I plug out my headphones (the internal speakers won't produce noise and I have to go through the whole repertoire again). This is driving me crazy and I don't know what it could possibly be. I have seen tons of threads about similar problems and all of them just say to reset the PRAM... Please help?