Hi ampayton,
Thank you for using the Support Forum. Remove any jobs in the print queue on your PC. Reboot both the PC and the printer. Make sure you have the latest firmware loaded for your machine. If it still fails try cleaning the toner density sensors. If none of this clears the issue please consider contacting your support centre for further assistance.
I've been having issues lately with my printer though it was fine for the first three months. I've reset each toner cartridge and tried restarting multiple times as well as updated firmware and drivers. The printer reads as though the black and magenta cartridges aren't being acknowledged by the printer (they just have an x on them on the menu) but when I try to refresh the toner through the settings it says a job is in progress and to try again later despite not having any jobs. I'm out of ideas and I'm worried that buying new cartridges will only encounter the same problems.