My iMac G5 has had this problem already for a little while, and I think it's in need of codecs reinstall. iTunes and QuickTime work normally, but that's about it. RealPlayer and Windows Media Player 9 play video, but without sound. Same goes for their respective browser plugins. I think it happened when I installed Myst V Demo, or when I was playing around with Flip4Mac. I know where the codecs are stored on a Windows machine, but how do I access them/reinstall them? Thanks for any help.