I've been on Win 7 64bit for a week and was able to solve the unidentified network issue within a day. Your circumstances may be different but this is what I did:
Go to Microsoft support and look-up Article ID: 929852.
How to disable certain Internet Protocol version 6 (IPv6) components in Windows Vista, Windows 7, and Windows Server 2008
I chose to fix it myself. This is a registry edit that's fairly simple and straight forward if you follow the directions.
I chose option #B:
Type 0xffffffff to disable all IPv6 components, except the IPv6 loopback interface. This value also configures Windows Vista to use Internet Protocol version 4 (IPv4) instead of IPv6 in prefix policies.
Another part of the puzzle was that my computer was connected via ethernet cable directly to my Uverse 2Wire RG router. (Basically bypassed one of my switches in hopes of faster connection speeds) I unplugged my direct connection and plugged into my 8 port switch, restarted and viola, no more issues!
So... if you're plugged directly into your router you might want to try a switch as a middleman and the registry edit if that doesn't fix it.
Good luck!