OK, apparently HP, Epson and Lexmark use smart chips that expire wether the cartridge is empty or not. There's a $20 rest tool for Epson and some hacks for HP. Also looks like customers are going to Canon to avoid the headache and expense. Apparently there is a class action lawsuit against the chippers.
General info:
http://pcbuyersguide.com/hardware/printers/smart_chips.html
Possible hack/work around:
http://www.atlascopy.com/newsletters/HP_Expiration_Dates.htm
Cutting to the chase, here's the workaround for what appears to be the HP all-in-1.... bottom of page
http://www.land.netonecom.net/tlp/ref/letters/hpPrinters.php