79 errors could be 3 different things, a bad DIMM, a bad network (JetDirect) card or a bad formatter. The first thing to do is find out is if the formatter is bad so you need to turn the printer off, remove all the memory and the network card from the printer and then turn the printer on. If you get the 79 error then the formatter is bad and needs to be replaced, call your service provider.
If no error then turn the printer off, put the memory in and then turn the printer on. If you have more than one DIMM, add the DIMM's one at a time so you can find out if one of the DIMM's is bad. If you get the 79 error then the DIMM is bad.
If no error from the memory, then turn the printer off and add the network card and turn the printer on. If the 79 error happens then you've got a bad network card.
HTH Joe Miller
joe.miller@flotech.net