[Alneyan]

Isn't it linked with a computer crash? I know I had the same problem a few months ago; it was solved by not crashing my computer, and, above all, turning off the writing Cache for my hard-drives (which was said to result in data loss in case of a crash).

I cannot swear the solution actually solved the problem, but my settings and bookmarks remained in place since then, so there may be a connection between the two.