Video to M6 conversion

I have converted a DVD to avi format and tried to download it to the M6 with the video converter software supplied with the player. If I stop after about 5 minutes of conversion everthing is fine both picture and sound. If I erase the flie from the M6 and start over and copy for 10 minutes or more nothing shows up on the M6 player when I start the video. The file shows approx 30mb of data but when I look at the file properties it says there is no infomation to display. Any suggestions?