I was thinking that perhaps win 7 is first connecting to a private share on your MBL. It would then try to use that same login for accessing any folder on the mbl, including public folders. Sort of the reverse of this thread.
http://community.wdc.com/t5/My-Book-Live/my-book-live-log-in-problem/m-p/260170/highlight/true#M4394
Do you have any mapping to the MBL? You might try the net del and then try.
Can you still get to \mybooklive\public\Photos or whatever other public folders you have on the MBL?
(note, the above path would be entered in the search field, not in a web browser.)
