I had exactly the same problem which went from that anoyance to a nightmare.  Now I have no library.  Happened out-of-the-blue.  This is a powerful pc [corei7] which is almost never put online - and then only for occasional windows updates.  No firewall or antivirus other Vista.

I have been working with SM tech support and we must have traded at least 30 emails over the past week.  I have tried virtually everything & still no library.  Tech support has been very responsive, but no solution. 

Been booting in Diagnostic mode & turning off everything that comes with start up.  Been dumping all kinds of files & forwarding them.  Nothing.  Been learning quite a few things about Vista, but no results.

I fear the next thing is they will ask me is to reload the OS.  Uggh.  Still have a few things to try.