Hi again,
Thanks for your concern everybody. I sorted it out and the only thing that was causing the trouble was a loose RAM on the bottom of it. It also used to hang up (Screen went blue) when put on lap. I just removed the RAM and reinserted it and WALLAH, its back to normal operation.
I tried the USB flash drive also and it doesn't cause any problem any more. Although I am confused as to how it removed the USB problem since it should only have rectified the lap thing but I am happy its functional again, take care!
Regards,
Chkmg