How to convert Gremlins from VOB format to WMV?

I cannot understand why but whenever I convert my Gremlins from VOB format to WMV, it is always unsuccessful. It always stops at 61% and then a message will come out saying “Error occurred during conversion -996. Please try again with another codec such as FFDShow.” Has anybody encountered this kind of error before with JetAudio and knows how to solve it? Please help me if you are. I will be very thankful for such help.
