I love my MP600! AND it's telling me that my larger Black ink cartridge can't be recognized. I've removed the cartridge and put it back in, and all the red lights are on like they should be, then I close the cover, and I get the same message. I've ordered a new cartridge, but in the meantime, I'd like to scan something to a PDF which has nothing to do with ink, but I get a message that maintenance is in progress and I can't scan until this is over.
AArgh.
I've also tried turning the printer off and back on.
Any suggestions?

That's a Canon, right? Did you try contacting Canon tech support?

But it sounds like, that the machine is detecting a problem cartrdige and won't come out of maintenance mode until its replaced. Effectively rendering the unit useless.

Thanks, ScottGem.
I got my new ink cartridge, and once I installed it, everything works find.
Kind of a drag, but still glad to have solved it, and glad to have a working printer again.

As a general rule I always keep a spare set of cartridges on hand for all my printers. When I pop in the spare, that's when I go out and buy a replacement. This way I am never without a spare for just such an emergency.