Canon IP5200 doesn't print black correctly unless color is present in the line

That is not a very good description of the problem, but it fits in the Subject bar. And I have to apologize for bringing up the fact that it is running with Microsoft XP, but I think it is a printer problem, not a software problem, and I would really appreciate any input you might have.

I have an IP5200 that is about a month old. After we ran out of black ink from the large cartridge (5PGBK) and mucked about trying to refill it, then found it was chipped, we got a new cartridge.

I just created several test pages, filling the page with different colored text. I was fortunate to find a font that leaves very little gap vertically between lines, so I really can see where it prints over the entire height of the page.

If the text is entirely black, the printer prints about a half inch, then skips about a half inch. If there is ANY color ANYWHERE on a line, it prints perfectly, even the black parts.

The printouts from head alignment and the nozzle check are perfect. I have uninstalled and reinstalled the printer, with the same results. We have not changed any software on the computer.

Any clues?