Hi Dave,
I have read your post on the forum relating to bright spots. I am having exactly the same problems as you. I have done many many tests, (probably the most of anyone) and no clear diagnosis yet just certain directions. I noticed you haven't posted for a while and I was wondering if you have had any diagnosis on this particular problem in the meantime? Could you e-mail me in case you read this at: holger(at)minddesign(dot)co(dot)uk
Best, Holger