Updated to 3.6.16 and all my bookmarks and links have gone. [SOLVED]

I upgraded to FF4 last week, didnt like it so reverted back to 3.6.15, today I come to use FF and it does an automatic update to 3.6.16, then updates an add on (URL fixer). When FF restarts all my bookmarks and links across the top of my browser have disappeared. Ive checked other profiles etc and there is nothing