My Sony Vaio hangs when I'm watching videos, then I hear the fan whirling like crazy and I would turn it off. When I boot it, it turns back to normal but then last night when I tried to turn it on it won't. Please help me with my problem. I haven't tried to boot it today but I'm hoping it would.
Your laptop may be overheating and shutting itself off to prevent damage to the machine. Are you using the laptop on a hard surface, or on a bed/blanket?
If it's on a soft surface, you may be suffocating the fan and the laptop will always overheat. If so, stop doing that! and put it on a hard flat surface.
It may help to blow into the fans exhaust (like a harmonica), this will knock loose any accumulated dust on the inside of the heatsink cooling fins. If it's dirty, you'll see the dust come out of the fan intake and improve cooling.
If your computer does not boot now, try unplugging it, removing the battery and with no power to the laptop, press and hold the power button for 30 seconds, replace battery, plug back in and attempt to start then.
Your symptoms definately fit the profile of heating issues, I would think a laptop cooler could be helpful here