DELL E514DW corrupted messages

I am finding that most of the messages and menu options displayed on the printer's LCD are gobbledygook.  It makes the menus quite difficult to use.  I thought perhaps this was a problem with the display until I noticed that if I access the printer by the printer's webpage on my LAN, the Device Status is shown as "Rep the ded", which is one of the messages I have seen displayed on the LCD.  

Has anybody else had this sort of problem?  Does anybody know a solution?

Thanks and regards