I've got PowerProducer 5.5 installed on a Vista 32-bit PC. All audio and video work fine with it, except for the AAC audio of some .mp4 files. The audio doesn't work in the Authoring environment, nor in the burnt disc. I installed PP5.5 on a Windows 7 PC and imported the same .mp4 files. Everything worked fine.

Anyone got any idea what could be causing the problem on the Vista machine? Any suggestions on fixes?