It could be an issue with your printers IP. If is is assigned through DHCP it might have changed. When the IP has changed from the IP when installing QTR it won't print.
You can either reinstall QTR to lwt it recognize the new IP or set a fixed one on the printer. This can be done with the 3880's menu/display on the printer (Network Setup). Reinstall QTR after this and let it know the new IP.