I'm behind a proxy that require authentication by means of user/pass.

I'm using Ubuntu 11.04, I think the proxy is "Squid".

Usually everything works fine, that means that the browser shows me the window to insert proxy user/pass and I can navigate.

The problem:

Sometimes the browser refuse to show the authentication windows and if I wait enough it gives me an error like:

Errore 130 (net::ERR_PROXY_CONNECTION_FAILED)

Even if I restart, disconnect, the situation doesn't change.

BUT on Windows the network (and the proxy) works..

So, bottomline what I know is:

• the network is working (though only on Windows)
• the Ubuntu configuration is ok (because i can navigate most days)

The problems resolves itself in a few hours but I don't understand why.

Some hints? Thanks in advance!

Andrea