Notebook battery and power problems

[chungskm]

Hi

I have a Sony vaio VGN-N11M/W. When i plug in my power cord with the battery still inside, it makes a trr sound and goes off. It works fine with direct power . The other problem is i have to press the power button hard and long to swith it on. It never switches on in the first attempt.

Any suggestion would be highly appreciated,

Thanks
Palden