ACM Failed to suggest Audio Decompression Format

This is the message I'm getting on a lot of files all of a sudden on Virtualdub 1.3 AND 1.4, I just formatted and re-installed windows XP (Wanted a clean install).

Am I missing a Codec? Any idea which one(s)? Should I just re-install Nimo with every option checked?

Any help is appreciated, Thanx!