Have your customers perform the following steps to correct the problem:
1) Using the Finder go to Applications, Utilities, Java and launch Java Web Start. This should open the Java Application Cache Viewer window.
2) In the Application Cache Viewer window highlight your labs ROES application. CTRL-Click on it or select the Application pull down from along the top of the screen and select "Remove Desktop Application".
3) CTRL-Click on it or select the Application pull down again and select "Create Desktop Application". Set the name and location and select OK.
ROES should now be able to launch using the newly created desktop application shortcut.