The Java File ... Could Not Be Launched

I have X.jar files that whenever I launch java opens (as I can see in the dock) and then immidately quits.

A few seconds later I get a popup:

"The Java JAR file "Whatever.jar" could not be launched. Check the console for possible error messages."

Typing "java -version" into terminal gives me this:

java version "1.7.0_09"

Java(TM) SE Runtime Environment (build 1.7.0_09-b05)

Java HotSpot(TM) 64-Bit Server VM (build 23.5-b02, mixed mode)

I've downloaded the latest Java from Apple: http://support.apple.com/kb/dl1572

I've also selected "Show Java Console" in the Java Preferences. No console appears when I launch a .jar file.

I also cannot locate a "Java Console.log" file anywhere that might be able to lead me to the actual error.

Any ideas?