I don't know if this applies to any particular codec...But when i have a problem that i can't find a solution to I try to think in a stupid way to figure out the problem

Split up movies usually have the same codec and settings...So instead of virtualdub trying to decode and then recode them into one AVI just let virtualdub take the direct stream and just combine it with out trying to decode and recode them.

Under the "Video" Menu click on "Direct Stream Copy". "Frame Rate" and Select Range should be the only 2 options left available above "Direct Stream Copy". Open and append the movies and save as usual/

I just tried 3 different movies and it worked fine. It only took about 2 to 3 minutes per movie. Same quality and everything.. If anyone else can try it and let me know their results please post here.

L8r OnE