Laptop not working...plz help

hi,

Three ago days when I woke up and started working on my laptop in the morning, it started normally from sleep mode. I surfed the net for sometime but after that it automatically opened up some windows (one of them was ease of access window) and shut down after loud fan running noise. I was surprised as it never happened before. I pressed the power button to boot it up. The capslock indicator light got automatically on, remained on for few seconds then got turned off. Meanwhile the windows logo appeared and I was asked the password. I started typing it. I would have pressed only 2 or 3 keys and then the keyboard stopped working. Capslock light got on again. Ease of access window appeared, I don't know why. Now not even cursor was moving. This all remained for around 3 minutes and then boom...laptop got shut down. Two more tries to boot it up but in these tries I didn't even got the password page, the lappy got shut down even before that.

In these three days I was only once logged in but that too for 3-5 minutes only. Most of the times I am asked password, capslock gets automatically on after some keystrokes, then comes the ease of access window, loud fan noise and shut down.

Is it some kind of virus (i use microsoft security essentials)? or some hardware/software failure?

I dunno what to do. Plz help.

laptop -- sony vaio (E series), core i5 processor, windows 7 home premium, 4 gb ram.