Enterprise M507 delayed printing and printing errors

[JBFC1125]

I have (2) of the HP Laserjet Enterprise M507 printers. Both printers are connected via USB, not on a network. In the past week, both printers will either delay printing a job for up to 15 minutes, or when I do NOT have anything in the print queue, the printers will randomly start printing. The display screen shows "guest printing" and prints random symbols. I cancel the jobs, but another one will pop up and eventually I have to turn the printer off. Also, when I do get a print job to go through, it will print  my job and then several pages of symbols right after. 

[Repairatrooper]

Check the installed drivers. Your problem description is common when a Microsoft IPP driver is installed. On your computer go to control panel>devices and printers and then right click on the icon for your printer and select printer properties from the drop down menu. Click on the advanced tab and check the driver description. If it is IPP or Class driver those are Microsoft native drivers and provide very poor performance. For the M507 I would recommend either the Standared UPD driver or Smart UPD driver.