I have got a HP deskjet 720c and have just replaced the ink cartirdges with new ones (pcworld's own make) and have followed the troubleshooting guide for printer alignment and it still dont help, all my documents have a shadowy look to them, this has never happened before and i'm not sure how to correct it, even the test page where it asks me to click one of the lines that look straight are all out of line, does anyone have any ideas??
Try taking the cart's out, and putting them back in, being careful to make sure they go in properly.
Also, it could be a bit of dust/fluff caught on the printhead. Even one small hair will smudge the ink and ruin your printouts.
Either that or a duff cart.
I remember i bought a new printer. within a week it produced absolutly rubbish prints. Turned out to be chinchilla hair, stuck on the print-heads...problem solved, via a bit or carefully cut bord, to keep goo from falling in to the printer...
Have a careful look at the test page, on the black writing it should look nice and sharp. If one of the cartridges are out of alignment you should see the guilty colour 'bleeding' over the edge of the black onto the white paper. You may have to use a magnifying glass to see it.
I must say, I have seen this happen on other printers but never seen it on HP, they are usually very good indeed. It might be worth getting the correct HP cartridges.