blubergeist,
Try version 3.57
HERE setup as oulined in
THIS post. Try a setting of "VFBS=high" to start with and if you have problems change it to "VFBS=medium".
Also pre-processing your video with VirtualDub
HERE will improve the quality of your AMV Conversions. There is a guide to using VirtualDub
HERE
HERE is a sample plus my VirtualDub settings. To load the settings into VirtualDub go to File>Load processing settings..... load your video and save as .avi. Then run the video through AMV Converter.