BleepingComputer.com: HP C4380 Photosmart

Thought you may like to add this to your help page>

My printer worked fine with a refilled cartridge until the ink level on the computer ran down then it would not work saying incompatible cartridge after much searching on the internet I could not really find anything relevant to the 350 and 351 cartridge,tried reinstalling the software which did not work, but what does seem to work is if you put the disk in and it will give you the option to uninstall certain components uninstall Hp solution centre.
This has worked on mine
Cheers Alan