There are two suggestions on this forum: [broken link removed] :
''What's probably happening is there is excess ink on caked on to the contacts on the carriage (I think that's what they're called). They're pretty easy to clean and the cleaning process takes about a minute. Just remove whatever cartridges are in the printer, take a cloth that will leave a minimal amount of lint, and wipe at the dark spongey contacts located just below where the cartridges would sit (that is, on my HP C4280, as other models might have them somewhere slightly different, but they should be right around the cartridges' spot). When the caked on ink is removed and all you are wiping at is the sponge, insert the new cartridge and the printer should work.''
or, failing that:
''1 - Hold the power and cancel button down (X)
2 - When it say enter special key combo press Blue, Green then Grey.
3 - Press BLUE again twice, now it says resets menu.
4 - Press the OK button and press blue twice to get to semi-full reset
5 - Press OK for semi-full reset, printer should shutdown. Wait for 30 secs before turning it back on using the power button and follow the prompts to set the language and the country. If this won't work, then you need to replace cartridges.''
Don't know whether either of the above will work, but they might be worth a try!
