i have had this issue when I used a graphic program to copy the Tarred image to the SD card partition. using the command line to un-tar the file into sd card solved the issue.
Is there any specific reason why you are not using the default sd card image?
Thanks for replying Husain. I did copy the tarred image via command line. I wanted to use latest kernel as it had relatively more drivers. Moreover I would get latest dsp via open embedded. I tried many things but my problem remains unsolved. So now I am using the default image. Thanks for helping