Printing in color adds blue ink to everything

I've just started having a new problem printing things with our HP printer. I've printed with this printer no problem in the past, but now all of a sudden it's not working so well. The only thing I did that I can think of was install the "gnome" package briefly, though I then removed it and its dependencies.

I've attached a photo so you can see what's going on.

The page in the middle is a test print from Trisquel in color, which I cancelled partway through (once I saw it was doing what I was looking for) to avoid wasting ink. The one on the right is a Trisquel print in grayscale, and the one on the left is a test print from the printer itself. Notice that the Trisquel color print has had cyan ink smeared all over it (literally, as in every single printable inch has been filled up with cyan ink), and it's so drooping wet with ink that fresh out of the printer, the paper feels and bends almost like it was dropped in a bathtub. You might also notice that the grayscale one seems to have done something similar, albeit on a much smaller scale and with black ink (although this is one I'm not certain about, it did print a lot slower than it should have as with the color print).

Based on the fact that the printer's own test print worked with no problems whatsoever, I have to conclude that this is a problem on my computer's end. Furthermore, the printer is actually slowing down, suggesting it's doing this deliberately rather than accidentally. There also have been no changes to the printer (not even an ink cartridge change) recently. So I've pretty much completely ruled out the possibility of there being a problem with the printer.

But I can't for the life of me understand why this would be happening. I've been forced in the meantime to use black-only mode, but this is not an acceptable permanent solution since I actually use the printer quite a lot and much of that is stuff that should be in color (Keeper of the Cards self-printed cards, in particular). Any ideas, anyone?