I have not seen this issue before but I was running 6.0.1 for a very short while. I would highly recommend that you upgrade to 6.0.1.3. There are tons of resolved bugs related to backup/restore and you could very well be facing one of them. In addition, there are tons of other bugs that are resolved with the latest version.
Give that a try and let us know if the issue is still there.
Thank you for rating helpful posts!