java.lang.IllegalArgumentException: The icon should not be n

I have a Java process that starts another Java GUI process (which uses JIDE).

When I ran it I saw a lot of “Can’t create cache file!”.
and saw this stacktrace:
Exception in thread “AWT-EventQueue-0” java.lang.IllegalArgumentException: The icon should not be null.
at com.jidesoft.icons.MenuCheckIcon.<init>(Unknown Source)
at com.jidesoft.plaf.vsnet.VsnetWindowsUtils.initComponentDefaultsWithMenu(Unknown Source)
at com.jidesoft.plaf.LookAndFeelFactory.installJideExtension(Unknown Source)
at com.jidesoft.plaf.LookAndFeelFactory.installJideExtension(Unknown Source)
at com.jidesoft.plaf.LookAndFeelFactory.installJideExtension(Unknown Source)
at com.jidesoft.plaf.LookAndFeelFactory.installDefaultLookAndFeelAndExtension(Unknown Source)

Running the GUI process directly won’t see the exception.
It only happens when the GUI process is started from another process using Runtime.getRunTime.exec

How do I solve this issue?
What and where are these “cache file” created?

Thanks,