So, I tried printing a Word document with fonts in black and other colors. I also included on the document a couple Word graphic shapes, as well as a quick little bmp I made in Paint with scribbles of different colors, including pure black.

In all cases, it was just the black that didn't show up. The colored font turned up just fine, so it doesn't seem to be the fonts that are the problem.

The client then tried replacing the black ink cartridge and the problem did not improve.

At this point I'm suspecting a printer failure. I'm not surprised, since HP printers these days are hunks of cheap plastic. God, I miss the Laserjet IIP. The client said the printer was printing fine yesterday or the day before, and she prints often, so it isn't an issue with the ink drying up or something...

I'll be dropping by her place tomorrow and trying to print to my HP H470 (yes, I hate that it's HP, but it's the most portable printer I could find).