laptop screen goes blank (not off, but green!)

ok, this is a strange one. I was using my laptop, playing with virtual dj (not at a gig thank god!) adn the screen just went blank, not off but a shade of bright green,,,,eh? Anyway, it doesn't seem that the computer crashed as the music was still playing.
I closed the lid then opened it again and the screen came back to the log on screen (as it normaly would after my lid has been closed)
and it allowed me to pick up where i left off, the music only twitched a bit but never stopped.

I have had a laptop that crashed when the fan was obstructed,,but that needed a restart,,,this doesn't seem like a crash to me?
Anyway, I moved the laptop off my lap onto a table where the fan was less obstructed and about 15 minutes later it did the same thing.

Any ideas?