handful of a title, isn't it?

ok seriously though, this problem is starting to drive me mad. for some reason whenever i print anything lately, there seems to be a weird purple tint over the picture. it even does this in gray scale. i thought it might be low ink, but after changing cartridges, the problem is still there. this is very strange, because i have had this printer for years, and it's never done anything like this before.

for reference, the printer model is an HP Deskjet 5440, and the color cartridge is HP C9361