HP C4480 Incompatible Print Ink Cartridge Fix
There are 2 ways to fix this, and either one is super easy.
If just leaving the cartridges out for a few minutes and them putting them back in doesn't work you can always reset the checksum by doing the following...
1: Press 'X' and the power button at the same time. It will display "Enter Special Key Combo"
2: In Order Press Blue, Green and then Grey
3: Press 'OK'
4: Press the blue button until you see "checksum for relock data input"
5: Press 'OK' twice (the first time will display a number)
6: Press X three times.
7: Presto! Start printing with your "incompatible ink"
Where I buy my ink: http://rover.ebay.com/rover/1/711-532...