Ever since I got my G5 1.8 (1.5GB RAM, OS 10.3.3), I've been having trouble selecting the sound output. Not only does it seem to revert back to "Digital Out" every time I start my Mac up, but you can't change it - if you go into Sound and click on "Internal Speakers", it highlights it, but then if I go into iTunes for example, and click Play, nothing happens - the song doesn't start playing. I can't get anything else from other apps to play back/output audio either. If I then go back into Sound, it will have gone back to Digital Out again. I've got some speakers connected to the line out on the back of my mac, and, sometimes, if I restart and then if the VERY first thing I do is go and change the output, then IMMEDIATELY launch iTunes or DVD or whatever, I can get it to play, and then it'll be ok until I shut down again. But often this takes 2/3 restarts to happen. Bit of a weird one eh??