I tried most everything else first. Updated drivers, flashed the printer memory, calibrated numerous times, soft resets, hard resets, you name it - I tried it. Yellow had the lowest level followed by Cyan and then Magenta. Pages left 150, 500 and 650 respectively. The Cyan and Magenta colors were the ones that were off kilter so I replaced them first thinking that might fix the problem. Like I said the Yellow had the lowest level of toner but it was showing aligned when I would calibrate the printer so I figured I would leave it alone. I replace the Magenta cartridge first and kept troubleshooting with no luck. I then replaced the Cyan cartridge and continued troubleshooting still without luck. I then read this post and decided to swap out the Yellow cartridge. Once I replaced the Yellow toner cartridge it took one calibration cycle to correct the misalignment problem.
Lost about 700 pages of color copies from replacing the cartridges before they were totally empty and for the price of these catridges thats a few $$$. Too bad HP can't figure this one out. Pretty frustrating with problem showing up for no explainable reason and then the lack of decent support from HP to help fix the problem. With all the complaints from everyone you would think HP would devote more attention to this problem.