Hi, It certainly sounds as if you have a connection problem considering that neither printer will print properly.
Try wiggling the USB cable while it is printing or try putting the USB lead in another USB port at the back of the computer. Is it also possible to try the printer on another computer??
Incidentally, if you do much printing just using black, it would pay you to get a black only cartridge as printing black with a colour cartridge uses all three inks and can work out very expensive.
You possibly have a black cartridge already but I thought it worth mentioning anyway!