My printer ink expired

I turned on my printer the other night and was greeted with a message saying that a few of my ink cartridges had expired and using expired ink voids your warranty. I bought my printer in Jan 06. It was the HP Photosmart 3310. I went with that model because I wanted an All-in-One with wireless networking built in. I’ve been pleased with the purchase. It taught me that Apple has not quite figured out printers in OS X (Leopard appears a little better). When I got it, it took a few emails with tech support before getting it to work. The wireless networking has been great, I don’t have to worry where to put the printer. Now it isn’t used all that much. How much does one really need to print? I’ve replaced 3 of the original ink cartridges, there might be 6 different ones in there. The originals are the ones complaining that they are expired. Its surprising that these originals are still around since the ones that come in the box have about a third of the ink that the replacements have. The expired ones are getting a little low. I’ll be ordering new ones shortly, but I’m waiting until they run out. I’ll take my chances with the expired ink.

What do you suppose happens after the ink expires? Do the colors come out wrong? Does the ink solidify and not come out? Does the printer start to smell?