HP Color Laserjet 3500 Problem

Question

I have an hp color laserjet 3500, a little over two years old. Today it decided to shift all the colors in a picture when it prints. I proofed the images earlier this week and ran several copies. Everything I print today is significantly darker with way too much red in it. I tested it by printing different files from different programs. So I know it's not just a problem with one specific image.The printer reports no errors. The cartridges still have ink. I have rebooted it and tried running the self-cleaning, calibration and troubleshooting diagnostics. All of the properties are set to auto in my control panel. Any ideas why it is suddenly shifting the color on everything I print? What else can I try?