I have a suggestion that you might have aready implemented.. Don't TURN off that firewall, just go into the security center control panel and click on the icon at the bottom for the firewall then another window will appear that has three tabs General, Exceptions, and Advanced..
Click on exceptions and check the file and print sharing box to enable file and print sharing. There is much much to much risk out there to turn that firewall off even in a peer to peer situation with connection sharing..