Not sure if this is proper forum but here it goes. I'm not even sure if it's an issue with printer or OS X. I emailed Epson support, but they were of a little help.
I have an Epson r3000 plugged directl into my Mac Pro running Mac OS X 10.6.8 Snow Leopard.
When I turn off the printer all USB ports on hubs stop working including the ports on my Apple Cinema Display. This inclues my keyboard/mouse hooked up to the USB ports on the display. They just freeze. However if I plug the mouse, for instance, direclty into the Mac Pro tower it works fine. I previoulsy had an Epson 2200 without any issue.