Just go to the Network and Sharing Center, you will see, Change advanced sharing settings' , click on that and you will see all the options as mentioned earlier. Just enable all the sharing options for Private, Guest or Public, and All Networks, these settings have caused problems in the past and it's different than it was on Windows 7.

This is about the only reason I can think of for not having access to file shares on the Windows 8 machine.

The C:>Users folder is shared out by default so that shouldn't be a problem but I'll check that next.