Thank you for those answers: changing the settings doesn't seem to have helped anything, however the problem does seem to have appeared after a daylight savings change. I was in another office for 6 weeks and the printer was unused over that time, but the clocks changed over while we were away which correlates with that bug.
I went to the Fiery website to download drivers and I had the choice of 1.0 or 1.2. According to the printer name (in my driver) I have 1.1, so not sure what to do. I have asked my local IT to look into it but I think we might ask Xerox to update it all for us just to be sure. If we do have 1.1 can it be upgraded to 1.2 as far as you know, or are you stuck with the version you get when the printer is installed? Seems odd there is no choice given for 1.1.