Hi all:
I encountered the same essential problem as all of you - my DeskJet 6122 would not function as such on the Windows 7 OS - though the exact nature of the problem and the ultimate solution differed somewhat from those listed in this thread.
I initially plugged the printer in with other peripherals
before I turned on my new computer (Dell Inspiron series) for the first time. Not advisable in any case, but whatever. My computer actually recognized the printer, but it was listed a driverless 'unknown device.' Obviously, uninstalling it and adding a new printer/installing a proxy
driver wasn't going to solve the problem. My solution was as follows:
1) Open 'properties' dialogue for the device.
2) Navigate to 'hardware' tab
3) Select 'USB Printing Support' and double click or select 'Properties,' new dialogue opens
4) On 'general' tab of new dialogue, hit 'Change Settings' button, another new dialogue opens
5) Hit '
driver' tab - you should now see the 'update
driver' button active, press it to open the driver mgmt dialogue
6) Select the compatible device (printer) and driver (HP 990c), click 'Next.' Printer should now work fine, though it will be named 'HP 990C' (which shouldn't matter, since the functionality of the printer is circumscribed by the 990C driver anyway).
I stress that this worked only because my computer recognized the printer as some kind of device when I first plugged it in; if your computer doesn't recognize any USB input from the device when you plug it in, then I submit that's a different (and deeper) problem than what this approach aims to solve.
Good luck!
~JohnQPublic