I have xbmc installed on a softmodded classic xbox and all of a sudden I cannot connect to the shared folders on my Windows 7 PC. Well, it can connect but it wants a username and password, but none exist on my computer. It's been several weeks since I last used it, but it was working fine then! and no particular changes I can think of aside from I guess a few Windows updates. I've seen reference online to Windows Live essentials causing issues with file sharing, but I don't even have that installed. And I made sure to tick 'turn off password protected sharing' in my advanced network setup. I had the guest account turned off and working fine before, and tried turning it on but no luck. I can access my shared folders fine from other Computers and a ps3. I've read a couple threads of similar situations on various folders and none of their solutions have worked.
I had this problem, but the "Turn off Password protected sharing" change worked for me.