HP error message : "incorrect black printer cartridge"

I have had an HP1210v PSC for about 2 years now. I recently got
some flashing lights for the check print cartridge error light.

The diagnostics in the HP director states that "the black
printer cartridge is the wrong kind". I have had the same
cartridge in there since installation, and I don't think
this is an "out of ink" problem.

I emailed HP, and they had several suggestions (none of which
worked, duh, like cleaning the contacts and resetting the printer
and whatnot). They have a patch which is supposed to fix this,
but when executed it gives the error message "did not find
an eleigible printer to update".

Hp states this patch always works, which, obviously, it doesn't.

They now say it must be a hardware problem, but if a patch exists,
I'm guessing it must be a software prob of some sort. I haven't
tried replacing the cartridge (20$), because I'm still guessing
its a software problem.

Any ideas???