After initial panic that maybe HD died on me and replacing one by one all the components I tried removing also 1Gb RAM and replacing it with old 256Mb RAM and things are back to normal with it. Thinking that found the problem went out and bought new 1Gb same model of RAM but today 100$ cheaper then 2 years ago. New one is also NOT working. Tried both slots and it is not working. Now I again placed 256Mb back in and it is working.