OK - I'll pay money for someone to solve this! :-(
Genuine offer, I'll pay £10 ($18) to whoever can solve this frustrating problem for me,
http://216.26.160.137/Forums/AspNetForums20/ShowPost.aspx?PostID=6881
Let me know if you want further info. I'm basically trying to create a function that converts from mp2 to mp3. It involved DirectShow, but I;ve got most of that worked out. My problem now is more to do with InterOps - at least I think it is.