Printer installed but not responding to print jobs

Question

I'm not quite sure how to intelligently ask this question so let me describe what happened.
I have a friend who asked for help in troubleshooting a problem with his printer.  His printer is a brand new HP Officejet 6600 sitting near his computer and is on his wifi network.  He can not print to it wirelessly from his iMac running Lion, but his wife can print wirelessly to it from another room on her iMac.  He can print using USB, though, but he prefers wireless because of the wiring situation in this room.  Plus, he bought for wireless printing.
When I got there I checked his System Preferences:Print & Fax and confirmed that his printer was installed and had the green idle light showing ready for a print job.  I tried to print and everything looked normal and showed that the job was sent to the printer and was 100% completed but the printer never responded.  I tried it from his wife's computer and confirmed that she was able to print a page with no problem.  I brought my MBP and joined his wifi network and added his printer and was also able to print.
So, I tried some basic troubleshooting steps trying to print after each one, and nothing worked.  I deleted and re-installed his printer, repaired permissions, restarted in Safe Boot, tried printing in a second user account, Reset printing system..., deleted all com.apple.print... preferences,  installed Onyx and ran the System Cleaning routines,  powered down/up the router/computer/printer, reset the wifi on the printer and rejoined his network, and probably a few other things I can't remember right now.
After doing all of this and throwing up my hands I tried to print again from my MBP to prove that I still could, and this time was not able to print.  It kept trying to send the job but the printer never responded.  His wife's iMac was still able to print, however.  This got me frustrated and I decided to ask this forum for help.
Oh, and here's some more information.  His wife has a printer next to her computer, an HP Officejet something (I forget, not 6600, though).  His iMac is able to print over wifi to this printer with no problem.  What the...?
What other things can I try? Does this point to something in the printer such as a bad wifi card, or something?  Any suggestions or ideas will be much appreciated.
Thanks

Answer 1

LilyLC, hold on to your chair you will not believe what happened today.  Bear with me while I give you all the details but you will want to read the entire story.
First, to answer your question in the first paragraph of that last post, his wife's printer is connected to his wifi and is using the driver installed by Apple and has been updated on the same date as his computer that I gave earlier.  She can print to her printer and so can he.  After the troubleshooting steps I have taken and took today I agree with your assessment about an intermittent issue with the printer, too, but let me tell you what I did today.
Before going to his house I decided to set up a second wifi LAN at his house using my router to check if his Airport Extreme (I incorrectly thought initially it was an Airport Express) router was the problem.  The thinking being that I have checked his printer and computer and nothing I have tried is making a difference, so the only thing left is his router.  So, I set up my router and joined his computer, printer, and my MBP, to the wifi and tried to print from both computers.  The printer still was NOT working!  That was a big disappointment since I just knew that was going to work.  I guess that eliminates the router.  I reconfigured his computer back to his wifi and proceeded to the next step.
I hadn't installed the drivers from the website you gave me earlier since I saw in Software Updates that he had updated to that same driver set already.  Now I got to thinking that maybe those files were corrupted somehow so I downloaded the drivers from the website you gave me and installed.  Deleted drivers from Print & Scan pane and installed the newly downloaded driver, tried to print, and that failed, too.
Next I tried your suggestion of using the LPD protocol instead of the HP JetDirect and that setup failed for some reason.  I reconfigured using the HP JetDirect, and that worked for printing, as before, but the scan function was not available, as before.
I was getting a little pressed for time today and had time to try one more thing, so I decided to forgo the new Location setup until tomorrow and instead chose to plug his printer directly into the Airport Extreme via USB and see what happened.  I deleted the IP driver and clicked the + to add the installed driver and was presented with an HP Officejet 6600 on the top line and lower down under "Nearby Printers" found an HP Officejet 6600 series [XXXXXX] and under that HP Officejet 6600 Fax.
I chose the first driver and installed and tried to print and was successful.  However, the scan function was not available.  So I deleted that driver and chose the second one.  I noticed immediately that the scan function was available.  Thinking I might have something I tried to print and was unsuccessful.  Mmm...printing works with the first driver but not the second and scan works for the second but not the first.  What's with THAT? 
This was really getting frustrating by this time and after much discussion with him I told him I thought the printer was the device at fault.  For some reason his printer just did not like his network.  I tried printing to his wife's computer and that worked great.  No problem there.  But for some reason his printer did not like his network and refused to work by setting up manually.
I recommended that he bring the printer back and exchange it for another printer.  He agreed and immediately boxed it up and left for the store.  I returned home to more friendlier surroundings.
Here's where it gets interesting, and it helps to know that my friend is in his mid-eighties.  About an hour later he calls and tells me he's sitting in the parking lot of Office Depot.  He tells me that when he was in the store discussing with Customer Service about an exchange it dawned on him out of the blue that he DIDN'T NEED TWO PRINTERS!!  He said that if he could print to his wife's computer today then he could print to it from now on.  I was speechless!!!  I told him I asked him at the beginning of all this why he had to have two printers, and at that time he said "trust me, we need two printers".  Ok.  He tells me he has no idea why he didn't realize that wifi worked differently than cable.  He thinks that maybe since his older two printers were each connected to his and his wife's computer these newer computers operated the same way too.  But he admits to me that he was the one who set the printers up on his wifi network, so why he didn't realize that only one printer was necessary with wifi he didn't know.  He was embarrassed.  He admitted to me that technology is very difficult for him to understand.  No kidding!!!
I didn't need to remind him how much time had been spent on this problem because he was quick to apologize and was very sorry for taking up so much of my time, and he really appreciated the effort.  I told him I didn't mind.
And I really didn't, because I learned so much from this experience by following your suggestions, LilyLC.  I never knew how to set up a printer using its IP address, and the protocols to use, and I never knew how to add new Locations in the Network pane and why it might be useful.  You also got me to considering other troubleshooting ideas I wouldn't have thought of otherwise.  So maybe my friend and I aren't that different after all.
I really appreciate all the suggestions, links, and ideas you offered during this effort, LilyLC.  I wish I could have determined the cause of the problem but, not knowing the inner workings of these devices, I can only assume that it had to have been the printer.
I bet I get a call from my friend a week from now saying that he just bought a second printer for his room because his knees can't take the walking from his room to his wife's room to get all of his printouts.  All I can say is THAT printer better work.
Thanks again, LilyLC, for all your time and help.  It was really appreciated!