Dell 3000cn. Display showing Load MDF letter plain 1 but it is loaded with paper already. Nothing outstanding in print queues. Any advice please? Thanks in advance..

http://office.manualsonline.com/manuals/mfg/canon/mp250.html

dont be surprised if its time for a replacement
once all in ones printer become unreliable they are throw away

check the page setting in the printer as well as in the print dialog box in the, if the problem persists then you have to send it for servicing

check whether the cartage is fix well or the paper is far from the area from where the printer starts printing.

When you loaded the paper in the tray, did you tell it that the paper was A4 - it may be that on the printer or in the queue definition on the computer that the paper size for that tray is set to something else (eg letter) and the print you are sending is A4 so it is looking for paper but only thinks it has other sizes available.

Turns out that the paper tray was damaged - the tray was unable to determine the correct paper size, despite fooling with the green paper stop. I had to compare it with a known-good tray to see the problem.

Using the printer panel; you need to change tray paper size from a4 to letter or the size you are using to print on.

1. Press the MENU button.
   
   
2. Press the down arrow until Tray Settings appears and press the button.
   
   
3. Press the down arrow until Paper Size appears and press the button.
   
   
4. Press the down arrow until the specific paper tray (Tray 1, Tray 2, or Multipurpose Feeder) appears and press the button.
   
   
5. Press the down arrow to select the specific paper size, and press the button.
   
   
6. Press the MENU button.

An astrick will appear to the right of the size paper that the printer currently has selected.

A lot of users have no idea how to change the MS Office default from US to UK .. so they have US spellings and US paper sizes (known as 'Letter' sized) .. and (of course) any Document that started life in USA keeps it's size until some-one changes it ... since Letter size is almost the same as A4 no-one cares UNTIL they come to print it ...

I'm sure you can guess the rest :-)

Yes, the Printer is looking in it's feed tray for Letter sized paper .. yes, Letter doc's will print just fine on A4 and most printers have a setting somewhere that lets it use A4 when asked for Letter (often called "automatic A4<>Letter convert" or some such)

NB. when time permits, perhaps the unfortunate users can have their MS Office apps. set to UK mode :-)

Make sure that you have set the same paper type on both the printer driver and on the printer itself, using the on-printer menu. When I get this message, I usually had forgotten to change the paper type on the printer.

if the printer is setup for A4 paper , it maybe that your p/c prog is trying to print using letter size.
microsoft tends to default to US sizes wjich are letter.
if using word check page setup for paper size

This is usually related to the way the tray or trays are configured on the printer or the way the program from which your printing from is configured. If you are using ms office, as an example, if the instructions to the printer from the software (ms office) say to print this document to the Multi Purpose Feeder tray (MPF) using plain paper and there is no plain paper in the MPF, you will get this error. Conversersly, if the printer's MPF is configured to print only legal size paper, and the software you are using is sending a print job to the printer telling it to use letter in the MPF, you will get this error. Basically, the printer settings and the settings from the software must match in order for this error to not occur. The settings for the printer can be changed usinig the operators panel of the printer. Directions for this should be available in the users manual or from support.dell.com. The setings for the software shold be in the print properties/preferences of the software being used.