Upon updating Windows 7 for the first time in a while and rebooting, I was soon horrified to discover that I was unable to connect to any remote hosts over the internet. Miffed, I immediately performed a System Restore but no connectivity was regained.
Looking a bit deeper, I soon realised that I could reach my router's configuration webpage and other machines on my local network, so quickly suspected a routing issue. I also noted that Windows thought I had two "networks", one my "Home Network" and one an "Unidentified Network". With only one NIC installed, I found this odd. I tried to use the options given to delete one of the two, but one seemed to be a bit of a ghost, with no real presence other than in that window.
With help from Steve Hathaway's answer to this thread, I found the answer: a phantom persistent route left in place by Windows pointing to 0.0.0.0 for no apparent reason.
Within an elevated command prompt, I ran
ROUTE DELETE 0.0.0.0 to delete the phantom route, then
IPCONFIG /RENEWALL to regain the proper route information. And then everything was fine.
Watch out for this one.
Regarding this post's title, yes I know that 0.0.0.0 isn't an address to "nowhere". I thought it was an apt title anyway.