Hi Robbbb,
I do suspect the colour cartridge being empty is the problem. It seems the printer is trying to calibrate the cartridges but is probably failing because the colour cartridge is empty. If you perform an alignment with a new colour cartridge, I imagine it will pass and cease to continue printing the alignment every time you turn the device on.
I suppose you do not want to buy the color cartridge because you generally do not print in color, and would rather not expend the money understandably so. If it helps, you can change your print settings to print in grayscale mode in the print preferences. Printing in grayscale would help you to conserve the colour ink, and save you from having to replace the colour cartridge on a frequent bases.
Hope this helps.