I would not use the conversion software on the Gmini 400 stock. I would download Pocket DivX Encoder. Available here http://www.pocketdivxencoder.net/
Its clean, safe, fun, really easy to use and works every time. I have been using it for a very long time and it works on all Archos products flawlessly. "You have to install a recent version of DIrectX (>9). No other soft or codec is required to make PocketDivXEncoder work." But you probably have this already if any newer games are installed on your computer.
If this program still can't convert your Die Hard audio, then the avi file your converting from is the problem, and I would check with wherever you got the file for the source of the problem.
I hope this helps your problem. Best of luck to you!