Recently my VPN PPTP connection stopped working. It seems to connect but then gets stuck on "Authenticating....." It never times out and I never get an error message.
As a sort of test, I tried entering a totally incorrect Account Name in Network Preferenceces for the VPN connection to see what happens. When I did that I immediately get an "Authentication Failed" message. I corrected the user name and it again gets stuck on "Authenticating....."
I restarted the computer and I have been trying to connect to and now it works:)