Gknot/Vdub Problem

When I am trying to encode, Vdub takes awhile, and the end result is I have a 16mb first pass file after which it says “Avi output: can not access something”. I was aiming for 233. I had this same problem with vdub and some other program awhile ago. I had gknot working, but I updated some things and removed some others in order to access b-frames and such. I have been encoding in xvid. This problem pops up with a huge variety of settings, I have been unable to find what causes it. Help please.