Manual Proxy Configuration Not Working?

Hey guys,

I'm trying to create firefox portables to use for each of the proxies I have.

When I go to manual proxy configuration and enter in details it seems to work, but if I exit firefox portable and then reload it I keep seeing "Problem loading page"

It doesn't even give me the window to put in username/password on loadd up.

Sometimes I just wait for a while and then the pop up comes up.

How can I make this work? Any ideas?