Webuser Forums: some files will convert and others won't. any thoughts please?

hi guy's i need some knowledgeble people to help me sort out why some files i'm converting refuse to be added to my i-pod. i have a set of 16 episodes all from the same place, all about the same length(175mb)in the Divx.avi format and all fully watchable on my pc. i was quite happily, and successfully, using Videora to convert them into an mp4 format for transfer and, after selecting the appropriate settings, I used the 1 click convert button and she would get on and do her thing. all was going incredibly well and smoothly until i noticed that episode 8 was not in the list. because i was somewhat in the flow, and by now rather pleased with myself at my new found skill, i'd already got up to episode 14 before realising that number 8 was not present. so i went back and tried again, using exactly the same method that i'd successfully used to convert all the other episodes, but the same thing happened again, it wouldn't upload. when i try to import that file into my i-tunes library only the briefest glimpse of the file upload flashes in the uploaded file window and nothing more. i've looked at the files' properties it's the same length and format as the others and i can watch the entire episode, from starting titles to end credits, on my pc so i know it plays ok. i even used a different converter, AVS, but the same thing happens.

so this is where i need some advice please guy's. is there something i can do, or is it a lost cause. any help as always is much appreciated.

p.s it now looks like episode 15 is also going to be a problem.

thanks

mikey b