If under a year, let HP get it fixed for you. This under 100 buck printer can not be repaired for less than a new printer.
http://reviews.cnet.com/multifunction-devices/hp-photosmart-c4480-all/4505-3181_7-33073984.html and other places seem to note this one has troubles.
Help! Our HP Photosmart C4480 has stopped printing black. At first it would simply sputter black, and now when you print anything text related you get a blank sheet of paper.
I've replaced the black ink cartridge three times and I continue to get the "low ink" warning. I've tried cleaning the print heads. Nothing seems to work. The color printing works fine.
It's hooked up to a Mac, but it won't print black from a PC either.
We've only had this printer a year or so and we use it sporadically, but when we need it, we need it. I hate the thought of buying another AIO, but I cannot seem to solve this problem.