I think best would be to exclude this parameter from detection - although it looks pretty inviting for attacks. Is there any way making the plugin not to send out those huge params?
Now that you mentioned it, I think that is a real atack. The URL: http://labor.labcei.unimore.it/68049/guppy467/users/office1.jpg is not mine. Someone is using the plugin to do something. Maybe is a flaw in the plugin. My version is old. I'm going to update that plugin, and see if the problem continues.