I spent several hours today trying to get the most basic Rails site possible running on my laptop and only recently succeeded. Initially, something prevented remote Ruby Gem installs from working at all (gem install would just hang), so I had to chase down all the gem files and download them manually. When I finally got all that done, WEBRick just wouldn't respond to requests. Everything started ok, but when I hit http://localhost:3000/ in my browser I got "Waiting for..." and nothing else. I eventually had to kill the cmd.exe process to even get WEBrick to exit.
After lots of running in circles (even attempting to install mongrel which proved difficult since I couldn't find a win32-service.gem >= version 0.5.0 anywhere) I discovered the issue. A few weeks ago I did a half a day's work for a remote client that required secure VPN access. I had to install some software that worked with the little key generator they mailed me. After ruling out all sorts of firewall and connectivity problems I thought of this Juniper Networks stuff they had me install and once I removed it everything worked fine. Both WEBrick and my remote gem installs functioned perfectly. Whatever it was doing was enough to mess up Ruby's network code, without bothering my browser or any .NET apps I wrote.