Hi Sudheer,

Yeah definitely something to do with the power. Its either the power supply unit like martin said or it is probably the power supplied to your house that keeps fluctuating. I'm guessing (by your username) that you are probably from India.. or a country where the power tends to fluctuate quite a bit. Thus causing the computer to shut down (well pretty much turn off abruptly). If that's the case then you might want to look into getting something like a UPS in order to prevent your computer from automatically turning off. Or it could be that the OS on your computer isn't installed properly (since you mention that the computer does boot).

Oh and the on and the floppy lights coming on for a second and then turning off is common, so that's nothing you have to worry about.

Hope this helps...
Risherz