Your not bound to get an answer until you list your printer make and model. An example of why this is important is that Epson printers have fixed printer heads, where HP has the print heads on the cartridges giving you a new print head with each cartridge. I haven't found this to be a strong point of HP printers though since the heads wear out faster than the ink (so much for refills). You're also not listing symptoms. If it was the heads, it seems like you would miss a color at a time, or it would act like it was printing but wouldn't. If you want help, you should provide all pertenant info. Also read the help files that accompany the drivers.