On which kind of server are you runing ?
Linux apache ?
Window IIS ? (If yes, which version).
This warning is a joomla warning message and not a JMS one.
If you want to ignore this warning message, you can add a test to verify that "QUERY_STRING" exists but I am not convinced this will solve your problem as this is a warning message and not a fatal error.
Perhaps you could have a look in Joomla bug tracker to see if you have info concerning this case.
If you want that we investigating on your server, this is also possible with our billable support that you can order at
www.jms2win.com/en/joomla-multisite?page...35&category_id=1