Best answer by Keith N
Thanks for taking the initiative and getting started on troubleshooting. A couple other things you may want to look deeper into are the permissions of the shared music folder as well as the impact of any antivirus software. Brands like Kaspersky and Norton block Sonos as it looks like a computer trying to access the files (music) on your computer. With regards to the sharing permissions- Be sure that when you find the folder that holds all your music, the properties allow for sharing on the local network.
Did you happen to see if a reboot of the router changes anything? Since the router determines how the data is routed, after these changes (computer names, sharing permissions) are changed it's a good idea to reboot the router.