If folk use that new email login and upgraded to 10 you see similar pleas. If this was my issue I'd try the sharing these folk write about. Example link follows.
You'll see the "Even if you are not in a homegroup, go to control panel, go to homegroup, create a homegroup, make everything available," among other comments.
I have installed MMJB v10 several times before but now I get a problem - the Library window doesn't display the files. All other windows are ok. The files are loaded, but window stays blank (blue).
I could use version 8.2 but i don't like the default skin. Where can I find more skins?