I was having an issue where Media Player would not build the library at all and the pop window that said "unable to perform operation." I renamed the file called ".meta_storage" to ".meta_storage_bak" and then as root, entered "reboot" on the command-line. I found this posted here:
http://www.internettablettalk.com/fo...ad.php?t=21356

After booting, when I opened Media Player the unable to perform operation message appeared briefly, but the library did rebuild. Seems ok now.