An unidentified network, in so far as Windows 7 is concerned, is typically one without a default gateway.
Have you tried to run the troubleshooter from within the Network and sharing center?
If I understand correctly, it worked at some point and now it doesn't or does it but intermittently? It looks like you may have already attempted to manually assign static values to your ip addressing scheme did that resolve the issue? Did you include the default gateway (usually your router's ip)? Did you add DNS servers at that time?
If it doesn't work at all, then perhaps a recent driver update is causing the problem try opening device manager, expand network adapters, double click or right click on your problem adapter and choose properties go to the driver tab and choose role back driver and see if that helps.