Execute this line in the CMD as Administrator (start > type ‘cmd’ > hit control+shift+enter) and paste this line (rightmousebutton > paste).

reg add HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\ /v LocalAccountTokenFilterPolicy /t REG_DWORD /d 1

Be sure to DISABLE your Homegroup and to enable file sharing in the Network & Sharing Center