Actually I have given up on tmpgenc completely. It now fails on the wmv files also. It is completely erratic, I can't find any pattern to it. I thought for awhile that it might be caused by conflict with other processes on the computer, so I shut everything down but the essentials. Same result. I tried another computer and got similar results. I notice that if I do anything on the computer while it is encoding, it will error out. Sometimes if I just click on one of the buttons in tmpgenc, even before starting encoding, it croaks. No other program I have ever used on this computer acts like this. I downloaded the Panasonic encoder and it works fine, and never blows up.