I have a message in the window which says "Remove and check black cartridge." I have changed the cartridge 3 times. I got it to work for awhile, then the message returned and no matter what I do, it won't go away and it won't print. The printer is connected directly to my PC. It will not print in color or black. Any help is greatly appreciated, as I really need to be able to use the printer to apply for jobs. Thanks!