Hey guys, this user in the Sony 1Z/1A thread was having trouble with his Sandisk SD cards: https://www.head-fi.org/threads/sony-nw-wm1z-wm1a.815841/page-1382#post-14271347
Then the user resolved the issue by following the steps mentioned in this post: https://www.head-fi.org/threads/sony-nw-wm1z-wm1a.815841/page-1383#post-14272120
Thats great , Thanks for the pointer. The SD card formater looks good. Will use that in the future.