I had a problem with intermittent failures in surfing on Windows 7, along with messages like this "Firefox can't establish a connection to xxx". Retrying the link would usually succeed within 3 or 4 attempts. IE was the same.
It's not a problem with the firewall or anti-virus because I've disabled both. I have 2 other computers on my network, one XP and one Vista, without this problem.
Rebooting the router helped, but the problem always reverted within a short period. I use a Netgear WGR614 router. Another symptom was that the Residential Gateway icon in the Network folder would show up after a router reboot (when it worked), but the icon later disapeared when the connection problems reappeared.
I've solved my problem by disabling UPnP on the router after I noticed that the Windows 7 PC was showing up as a UPnP device in the router web page. Of course, I've disabled UPnP on my router which doesn't sound right. I don't know too much about networking, so I'd like to know if there's a better way of restoring my ability to surf, and what problems I might experience by disabling UPnP.