Laptop powers on but it doesn't turn on?!

[javaman12]

I was taking a look at my girlfriend's laptop because she said it wouldn't turn on anymore, so when I plugged it in and powered it up, I see the power light come on and the HDD spin, but nothing comes on the screen. The laptop is a HP Pavillion dv2000 running Windows Vista.

The weird thing is, I can get it to turn on and boot into Windows if I hold down the power button for about 3 seconds to shut it down. Then when I hit the power button again, it can boot up to Windows and I get the login screen. However, when I hit the shutdown button from that same screen, then hit the power button to turn it on, I get the same problem of it "turning on" but with nothing on the screen. This is all while the AC adaptor is plugged in, so I dont think its a battery issue.

Whats going on here?!