You can go to admin/configuration/theme & layout/settings and click the redX at the side of the theme you were using.
Then clear cache and you should be OK
glad to help
Congrats on your new upgraded forum
Thanks, that did it. Seems I've got a few old themes in there, time to hit the X on those too. No errors in log either so far
Now its time for a new theme and some mods. (In other words, time to screw it up

)
The advise has been great here guys and I will look back on it when its time to do the final gold SMF release... Whenever that may be.
Thanks again for sticking with me on this one.
All the best for now.
Bigscreen.