Joe,
If you are converting at the 160x120 setting in 4.03 it is actually converting your AMV files at 176x128 which is why they are crashing.
If you play one on your PC with AMV Player and right click on the picture while it is running and select poperties you will see the size. 4.03 is only any good if you have a 1.5 LCD and want 128x128 or 128x96 but even then you have to unlock the settings by editing the AmvTransform.ini and changing to CHIPTYPE=0.
If you want 3.57 it is in the Download section
HERE and you can find how to set it up
HERE
If you want to improve the quality of your AMV files you can pre-process them with VirtualDub to resize, crop etc. There is a guide on how to use VirtualDub
HERE and you can download it
HERE