Thanks for the responses gents and I finally got it to work last night.
I had the settings at 150 x 120 and just for the heck of it I changed the 150 to 140 and it worked. I suspect that the SP gods are a fickle bunch and my lack of playing time was taken as being disrespectful to their needs.
Whoo hoo, it's off to blow something up on a bigger map...
