You know the usual stuff. Check power and data cables, make sure the printer is turned on, and confirm that no paper is jammed inside the unit. Then open the Printers and Faxes window to see whether the printer you're using is set as the default. If it isn't, applications will blithely send print jobs off to another target, whether or not it's installed on your PC. Finally, print a test page using your printer's driver software, to rule out the existence of a problem with the specific application you're using.

Most printers sold over the past three years use the Universal Serial Bus to connect to PCs--but USB can be pretty flaky. If you notice intermittent printer outages, unplug the USB cable from the printer and then plug it back in after about 30 seconds. If your print job resumes, you may have a faulty connection or an overloaded USB bus. If the problem recurs, unplug a few noncritical USB devices and see if that solves the problem.

Check the print queue. Jobs that are reported as complete when nothing comes out at the other end indicate an issue with the printer itself. You might try cycling the printer on and off. Of course, frequent paper jams, misaligned prints, and mangled output paper are all indicators of a mechanical problem.