If you have cleared the print queue so there are no outstanding 'faulty' files; it's worth knowing that the 79.00 error can also be caused by poorly fitting or incompatible memory cards.
To clear the printer queue on PC
click on start
click on run
scroll down to print spooler
right click on this service then press restart
exit out and try again other wise continue below..
Can you make sure they are firmly mounted?
Remove all communication cables so that only the power cable is connected.
Remove the Jetdirect card, if installed.
Remove any other accessories, such as the envelope feeder.
Hold down the green "GO" button.
Turn the printer on.
When the words "Cold Reset" appear in the display, release the green "GO" button.
When "Offline" appears in the display, press the green "GO" button. "Ready" should appear in the display.
NOTE: If the words "Cold Reset" do not appear in the display, hold the
"GO" button down until you hear the motors rotate. The words "Restoring
Factory Settings" will appear in the display if the "Cold Reset" was
Turn the printer off once the printer displays the “Ready” message.
Reinstall each of the above-mentioned components, one at a time,
turning the printer on and off again each time a component is
Continue installing and power-cycling until all accessories are installed and the printer is at a “Ready” state.
If it is determined that one of the components is responsible for the 79.00FE error, refer to next.
If the printer will not return to a “Ready” state after removing all of
the components and performing the cold reset, try a different power
source by moving the printer to a different location and plugging the
power cord directly into the wall.
If the printer continues to display the 79.00FE error, upgrade the
firmware. A firmware DIMM can be obtained from the HP Parts Store at http://www.hp.com/buy/parts
. Version 6.36 Firmware DIMM is Part Number C4251-67905; however, part numbers are subject to change without notice.
If the printer still continues to display the error, contact HP for further assistance.