My guess is that you have a really old jEmplode installer and you just replaced jemplode.jar, right? I'm pretty sure the Main class has changed to another package ... To fix that, edit jEmplode.lax in your installer directory and search for "org.jempeg.empeg.emplode.Main" and change it to "org.jempeg.empeg.manager.Main" (I think that's the package it's in now). alternatively you can just run jEmplode by double-clicking on jemplode.jar or running it "java -jar jemplode.jar" from the commandline.

ms