Turn off the Printer and remove the communication cables (USB or Ethernet, depending on Set-up).
Turn the Printer on and verify if error recurs.
If the error has recurred, please re-set the Printers Defaults. C3760dn: -> Press Menu Button on the Control Panel. -> Press Down Arrow until Admin Menu is displayed and Select. -> Press Down Arrow until Maintenance is displayed and Select. -> Press Down Arrow until Reset Defaults is displayed and Select. -> The Printer's defaults should now be reset. C3765dnf: -> Press the Info Button on the Control Panel. -> On the LCD Touchscreen Select the Tools Tab. -> On the LCD Touchscreen Select Admin. -> On the LCD Touchscreen Select Maintenance. -> On the LCD Touchscreen Select Reset Defaults. -> The Printer's defaults should now be reset.
Restart the Printer and verify if error has recurred.