Im having this problem where when i import a video file, there will be no audio, and i know it can be imported in because ive imported it in before, but now when i go back to my old projects the audio thats with the video says media offline, i can import mp3 files normally and when i open my file in gspot it says codec(s) installed,

Ive installed:
CCCP, ffdshow,
lame acm mp3,
morgan M-JPEG and
xvid codecs,

Im on windows 7 and ive tried vegas 7 and 8 and still no audio shows up when I import my videos, its nt windows 7 either cause when the rc was released i installed vegas and the audio shows up normally, and everything was fine, does anyone know whats wrong? can someone help me with this problem please?