J2E’s (Jazz 2 Episodes) are files that appear at the main single player selection screen. There are 7 offical episodes (excluding Home Cooked Levels) in Jazz 2. If there are more than 8 episodes in Jazz Jackrabbit 2, it will crash. Jazz 2 will also crash if any of the official episodes are missing (excluding Sharewhare, Christmas Chronicles and TSF). In TSF, you may delete the offical episodes if you want to fill it up with custom ones.
Eat your lima beans, Johnny.