Ahhh, here we go. Here’s the fix for the problem I described below, should any of you run into it. It’s probably your firewall — no, you weren’t dumb enough to leave it on. Check your control panel. Access the Firewall. It may say it can’t open due to an unspecified problem. That’s a dead giveaway. Even if it opens, try this anyway. You need to install a reg file called “sharedaccess.reg”.
After you merge it into your registry, reboot the computer. After reboot, go to the Start Menu->Run. Type “netsh firewall reset”, without the quotes. Wait for it to finish. Then go back to the Firewall control panel and turn it off.
Should work now!