I wonder if something you installed/uninstalled deleted them, or if you use a program like appZapper if it deleted them.

However, wouldn't you be prompted for a root user password if something you were doing was going to delete system related files?

Yes, I certainly should have been notified of any changes. I've never installed any app removing tools, so that can't be it.

As someone pointed out on the forums, the fact that the entire file sharing system crashes due to a missing preferences file is quite inane -- it should just recreate the necessary plist file if it's not there, as all our other apps do!

-rob.

Did you file a bug report?