The behaviour was as follows.
1. Put the machine to sleep
2. Resume the machine, everything seems to start, but the display is black (not signal out of range)
I turned off the require password section to see if it was related to this and I could now see my desktop accept it was a zoomed in version of my desktop, zoomed in to the bottom right corner of the screen, but missing the windows bottom bar. Icons and windows that were overlapping that portion of the screen also did not appear.
moving the mouse around I found that I could make my mouse cursor appear on the screen. I could right click to obtain the context menu I selected Nvidia control panel and suddenly my desktop was back to normal.
After further investigation I found that although everything was fine on boot up. resuming from sleep appeared to enable a 1900*1600 generic pnp driver from dvi socket 2 and set this as the main display and set my monitor that was plugged in to dvi socket 1 as and extended desktop from socket 1. This mean that the real desktop was appearing on a phantom second monitor which at no point has existed. This second monitor did not appear in the drop down list from a standard boot, but would always appear after a sleep or hibernate. I have disabled this driver and now I can use sleep mode again!!!
After I fixed the problem I only found one other person who appears to have experienced this issue. I am sure we cannot be the only ones, so hopefully this post will help someone with the same annoying issue.