Epson r200

Sounds like you may have a leak of a dark ink into the others. Remove all the ink carts and blot the area where they sit with tissue. If there is a lot of dark ink in the area, then this may suggest there ink leaking from the black cart and getting into the wicks of the other colours.

If the problem only occurs with the CD caddy in place, try an under head cleaning session to make sure the bottom of the head is not dragging on the surfaces.