Where are you trying to connect from? Is it a university network or something like that?

Are you using any proxies?
You can check them like this:
Firefox:
[Edit > Preferences] or [Tools > Preferences]
On the General tab, click Connection Settings.
If "Direct connection to the Internet" is selected, you aren't using a proxy. Otherwise you are.

IE:
Tools > Internet options
Click the Connections tab, and then the LAN Settings button.
If you have a tick in any box EXCEPT the first one, you ARE using a proxy.

As long as you're not on a university network or anything like that (a network not owned by you), you shouldn't need proxies. So disable them in the screens above if you are.

Also, if you can replicate the error, and post the exact message, that would be helpful. If it has come from EoFF, one of the admins here probably knows something about it.