Phantom non existent external monitor on Mac book pro

Hi all, whenever I open my mac book pro, or wake it from sleep, the screen turns blue and it auto-detects a monitor that is not attached - a generic VGA display - the image at the following URL displays when an external monitor is NOT attached:

http://ellington.tvu.ac.uk/images/displays.png

I have to click 'detect displays' between 8 and 14 (sometimes more) times to trigger another detect routine that always changes to reflect the actual state of monitors.

I have a cinema display and when connected to the MBP - on start-up or awaking from sleep, the MBP often fails to detect the connected monitor and yet displays the same display status as above a generic VGA display - click 'detect displays' 8-14 times and it detects the cinema display. Whenever the machine / display sleeps, it seems to be a lottery as to whether the true display status is retained or whether the MBP detects the phantom monitor, blackens the cinema display and requires the (getting very tedious now) detection routine to get back to what's expect. At that point, all windows have resized and shifted position. I've described the problem to several in-store genius's with no obvious answer. I did not do a clean install from Tiger, but wonder if it would've helped.
What do you reckon? Hardware failing or some strange software problem?
Thanks in advance, Ian Grant