Canon Pixma MP 800 printing Issue (heavy black...

Question

When printing from a PC or when copying,  a large (1/4" wide) black line appears on the opposite side (that is being printed on) of the sheet of paper.

It appears that before  printing begins a large drop of black ink is released before the paper arrives creating a puddle that is then spread across the back side of the printed document.

We have changed ink cartridges and it hasn't solved the problem.

Almost appears to be a software/signal problem sending a command to open the ink cartridge before the print information has arrived.

Any idea what's causing this and how to proceed?