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Are you using the same version of the javac command on the different computers?

The code you posted will NOT compile because the import statement needed for the JOptonPane class is not there.
You...

Your posted code does not have the import statements needed.
You need to post ALL of your code.

You should not name your classes with a Java SE class name.
Make your name unique by adding My: MyEvent.

Did you post ALL of the code for the two classes? Or did you leave some statements off?
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