Virtualdub Bug when converting from mkv to avi

Hello,

I'm using this avs code to open an mkv file inside virtualdub
DirectShowSource("C:\DVD\title00.mkv", FPS=30,convertfps=true)

But each time and in many different videos virtualdub is choosing a random frame from the movie and add it to the beginning of the video then the movie starts.

For video compression i'm using XVID one pass max quality.
Using 2 filters: resize and box blur.

What to do to avoid this?

Thanks.