Hewlett Packard HP Photosmart 6520 printer-Black Ink Jet Problems With Them All Nationwide

 I purchased an HP Photosmart 6520 a couple of years ago, used it very little in my home, but have spent hundreds of dollars on in cartridges.  It holds 3 colored and 1 black cartridge.  I thought the black cartridge was empty because it stopped printing but the computer showed it full.  I took it back to Office Depot and they replaced it free.  I put in the new one and it won't print either.  I checked the HP Printer site for complaints and there are hundreds all relating to this black ink cartridge that stops printing after a while.  My complaint is that HP is doing nothing about this problem, yet continues to sell these printers in the retail stores.  Office Depot still carries them, which is where I purchased mine.  My warranty is, of course up, but I am furious that HP would continue selling these defective machines after so many complaints, online and other wise.  I wish I had purchased HP stock years ago.  Who knew they would make billions just selling ink cartridges????  I just purchased a Cxxxx Laser Printer and love it, even though it's black and white only!