my laptop dell cant display anything when i switch it on, it takes time for the fun to start and when it does, it displays nothing, all this started when i upgraded th OS from windows xp tp windows 7 pro. sometimes i get a beep sound sometimes no sound.
Besides the OS upgrade, have you made any hardware changes to your laptop? It could be a BIOS upgrade that's needed, but since you said that you couldn't see anything on the display, there could be a video card problem or problem with the motherboard itself.
If your laptop is out of warranty, you could open it to clean the components, because the dust might also be the problem as well as the overheating.
My other suggestion is that your North Bridge might be failing, but to be sure, you could go to a PC expert in order to make the tests.