Fixing Lame Mpeg 3 files.

Can anyone recommend a program that can extract broken Lame Mpeg 3 files from a divx movie file and fix it.

The most important part is the fixing. I have virtualdub etc but the audio is screwed. I think the header for the audio file needs to be fixed. For some reason, it cannot decompress the audio even though I have the Lame mepg 3 codec installed and it works for 95% of my films.

So something is screwy for just 5% of my films.