I was unable to see what was displayed on the monitor at the time as it was not working but since then I have connected another monitor and found that an error message was being displayed saying " An unexpected error occurred the last time the desk was used!" and asked if I wanted to save the error data to memory stick.
I did not have a USB stick in at the time and the software version is 4.2.0 7/9/2007 LNX.
I saved the error data to memory stick and the desk booted up and so far appears to be operating correctly.
I have attached the error file for your information.DEBUG.DAT