When I power on my laptop the screen is not being detected. If I connect an external display(TV via HDMI) I can use it but obviously this isnt ideal. My first thoughts were a broken LCD or damaged connections but after playing with it and after a few restarts i noticed the screen working intermittently. The screen is perfect when it works so this has put me off the idea of getting a new LCD for the machine. Or at least exploring other, cheaper alternatives first. I think this first started happening shortly after I used the HDMI out for the first time. Im wondering if this could have had some effect? Could it be something stupid to do with the video card and resolution/default settings?
Could be a faulty or broken ribbon cable (the one that runs between the display and mainboard). Change that first - if it doesn't fix the problem, then you've likely a screen (much less likely, though still possible, a mainboard) fault.
I have exactly the same problem. Did you ever figure out what was going on?