Make sure on the 7 pc that the network location awareness service is set to automatic and running.
Do the same for the TCP/IP NetBIOS Helper service. Then, check the network adapter properties itself, in Network and Sharing Center under IPv4 settings, that NetBIOS is set to Enable (not Default.) - To get there, click Local Area Connection, Properties, double click IPv4 line, Advanced, WINS tab. Reboot after saving any changes.
Actually, I can take a look at the services for you to make sure all are well on the 7 pc. Type msinfo32 in the start menu then press enter. File | save on the screen that opens. Then zip the saved file and attach to a post using the paperclip above where you type, in advanced mode reply.