Norton VPN issue

I added Norton VPN to my Windows 7 64 bit PC several months ago. During the last few weeks a window randomly pops up asking me to log into the VPN. I carefully enter my user ID and password. Sometimes I press enter and everything works fine. Other, completely random times Norton VPN displays an error message with no explanation and I have to manually shut down the VPN and restart it. I also noted that there is no place for me to check for updates for the VPN and have no idea if it automatically updates with no indication of doing so. I do know that the VPN is working because a few sites I visit have a high level of security and do not recognize a random IP address. I revert back to my regular IP address, log on and, when finished, go back an turn on the VPN.

All that being said, my question is why does the VPN randomly suddenly request me to sign in and even more important why does it sometimes not accept my CAREFULLY entered login and sometimes reject it?