I use the firefox to access internet through my university proxy. I type my user account and my password. Recently, firefox is not showing the authentication popup, where I type my user account and my password, so I cannot access my university network. I haven't changed the proxy configuration (I've checked it, it is as it should be). When I try to access any website, I get the message "cache access denied" and it says that I have to authenticate to have access to it. However, there is no authentication window to enter my user account and password. I've tried to configure Chrome and Safari, and they worked perfectly. My computer is a mac running mavericks.