Epson 4880 large format printer only printing within A4 confines.

Hi,

I'm a screen printer so rely heavily on my Epson 4880 to print films and transparencies up to A2 in size.
I have had the printer for 2 months and have experienced no difficulties, in fact the complete opposite.

Today, no matter what size paper stock is in the tray or selected in my print driver menu, it will only print A4 in size onto the paper, essentially shrinking and cropping my image appropriately, as if it isn't taking on board the fact there is A3 paper in there and that is what the document size is.

I have tried all manner of driver and printer settings for the past 4 hours and am absolutely lost, and Epson's help is completely useless.

Can anyone suggest what may be wrong before i pay for a technician to come and fix it?

Thanks for any help, it needs fixing ASAP or my orders are screwed!
-Alex