Dave,
Not sure yet. I have just tried a totally new one, in case there was some corruption in the previous - just 4 walls, ceiling and 1 light. First render beautiful. Clicked Reset Radiosity and try again - even from the first time the image starts to appear it is just wahsed out completely - the final image was totally white. However when I closed the Real View dialog box and rendered again it was OK. So I assume the Reset is not working or does not do what I thought it was supposed to do. I have sent the original file to Jack to see if he can see anything but it does seem to be that if I close the Real View dialog and re-open it, it is OK.
Allan