You may have received a security warning when connecting to the Internet as follows:
“File and printer sharing is running on the TCP/IP connection you will use to access the Internet. Other users on the Internet might be able to access your files.
Would you like Windows to disable file and printer sharing on the TCP/IP connection to the Internet?”
If you answered Yes, it might be cause of the problem. Go into the Control Panel, Network, click on the instance of TCP/IP bound to the network adapter, select Properties, Bindings, and check the File and Printer Sharing for Microsoft Networks check box. This property for instances of TCP/IP for the network adapter and dial-up, etc. can be controlled separately. Larry