Try switching the printer off *AND* unplugging the mains lead for a few minutes to see if that 'resets' it. I have an HP PSC 1215 and its paper feed is a disaster area! Other than that it is a delight for printing scanning & copying.
<<< "The service 'Print Spooler' is preventing the machine from entering standby. Try stopping the service and try again.'" I have no idea how to stop the service. >>>
Right click "My Computer" and select Manage. In the Computer Management window that opens, click the [+] beside Services and Applications to expand it and then highlight Services. In the right pane, scroll down to Print Spooler, double click it and, in its Properties, click "Stop". Click "OK" in the Properties box to close it. Now reboot the PC which will automatically restart the Print Spooler, but there should no longer be any outstanding jobs in the Print Queue.