Print a configuration report to see if it is a driver (only things coming from your PC) or hardware (anything output in color no matter the source) problem.
If it is just the PC, it will be an app or driver issue, if it happens from 2 applications, it is the driver (uninstall and download/install a new one)
If the config sheet does it too, its a drum/imaging unit issue. Swap the cyan(2) and magenta(3) drums and reprint the same job 10 times, if the issue moves to a magenta background, replace that drum (3).
If it doesn't follow the drum swap it will be a belt or developer issue, I will leave that for Gabiene (or someone else who handles the hardware side of things) to answer