Ok, let's start off by saying i am not bashing Apple, nor am i basing HP. Both are fine companies who make some fine products, though both do manage to screw up now and then. Somewhere along the line one or the other or maybe both managed to slip something in or leave something out, that effects printing under Lion. I've checked around the net and there are hundreds of complaints about different printers having printing problems under Lion, so it is not just my system where the problem lies.

I have 3 printers. Printer #1 is an HP 2420 b&w. I use it mostly for b&w only stuff and connect to my desktop MacPro using usb. Everything works fine. Printer #2 is an HP Photosmart Plus that i connect to using wireless. I use it for small jobs that require color. Every thing works fine. Printer # 3 is an HP4550 color that i use for larger jobs like printing dvd labels, and making color masters for a couple of monthly news magazines, i connect to this printer using usb. This printer is the one i am having problems with.

I am running Lion 10.7.1 and the problem i am having when trying to use this printer is that it keeps telling me the printer isn't connected. I have deleted the printer from the print & scan section and reinstalled it. When i add a printer it comes up showing the 4550 printer just fine, but when i try and print to it i get the "not connected" error. I also installed the latest HP drivers from Apple.

Now it gets interesting... taking my old windows laptop running XP i plug into the usb port with the 4550 and presto up it comes and installs. When i try to print to the printer, IT PRINTS fine.

Next i use my MacbookPro running Snow Leopard, plug into its usb port and add a printer, up comes the 4550, installs, and shows online. When i try to print it prints fine.

This printer has worked just fine for 7 - 8 years. I bought it when i was still using my original old Mac G5, it has worked fine with the wife's G5 iMac, has worked with my MacPro intel, has worked with the wife's iMac intel and does works with my MacbookPro and works with my Winders XP laptop. Why doesn't it work now with the MacPro? Only difference between now and 4 years ago is the MacPro is now running under Lion, while the MacbookPro is under Snow.

Anyone have any idea as to what is going on?

Have you installed HP Printer Drivers v.2.7? This should have come through Software Update.

http://support.apple.com/kb/DL907

Yes i installed the drivers and it shows version 18.2 when i check the printer in prefs.

I thought at first something had gone wrong in the printer, maybe a bad usb port or something, but both laptops print just fine with it. Then i thought maybe a bad usb port in the MacPro, but both the 2420 and the Photosmart both work fine with it as does every other usb device that i have.

If you have not tried creating a new user account and operating the printer from there, that would be my next step.