Sounds more like your backlight or its power supply (also called the inverter) is failing.

Contact Dell for a warranty repair.

 

My 4150, which is 18 months old and out of warranty, has a similar problem. I have to reboot/shutdown a lot of time to bring the "black" screen back to normal.

How do I know whether it is due to the problem of bad backlight or inverter?

Thanks,

Kevin

Should I replace backlight only, or inverter only, or both?

Thanks.

It almost certainly is - the only real way to know is to replace the backlight and inverter - the parts are not expensive (under $50 for both).  Labor will run $100 or so at a computer shop.

 

I would order both parts - if you order just the bulb, and the inverter is faulty, you'll have to pay shipping or labor to replace the other part.

If the system is under warranty, let Dell do the repair.

 

Where can you find an inverter for a 600M for $50?  Mine goes blank intermittantly, and I called Dell and they only sell the inverter with the lcd panel for $380.  I checked with a local shop, and they don't have the parts, would have to order from Dell.  I've searched e-bay, etc. and no one has the inverter for the 600M.