Dell Vostro Running Vista Can't Connect To Public Wifi

I'm using a Dell Vostro, running Win Vista with all updates. I have Trend Micro Titanium and Comodo Firewall. I primarily use Firefox (completely updated) but also have IE 9. Until a few days ago I regularly connected to various public WIFIs, by: connecting to the WIFI network, opening Firefox which would then automatically take me the network's (Panera for example) user agreement page, clicking on "I accept" or "I agree" then gaining access to the internet. Two days ago I was at a local establishment where I have connected before. I connected to their network and opened Firefox as usual. Instead of connecting to their user agreement page as usual, Firefox tried to connect to my homepage (Washington Post) and failed.

The network icon in the sys tray showed I was connected to the local network but with local access only. This has now happened three times in three different public locations over the past 2 days. Each time I've successfully connect to the network but when opening Firefox or IE9 I am not directed to the user agreement page and therefore am not gaining access to the internet.Normally in the past once I had connected to the local network and opened my browser Comodo would open a warning window asking me if I wished to continue. This also is no longer happening as Comodo is not detecting me being connected to the internet, I'm sure.