Warning: Invalid argument supplied

Just started getting this warning! Does anyone know what I need to do to fix it?

Warning: Invalid argument supplied for foreach() in /hermes/bosweb/web132/b1326/ipg.youarewelcomehereorg/wp-content/plugins/simple-google-calendar-widget/simple_gcal.php on line 122

Thanks

http://wordpress.org/extend/plugins/simple-google-calendar-widget/