There is no Internet connection
There is something wrong with the proxy server, or the address is incorrect.
Try:
Contacting the system admin
Checking the proxy address
Running Windows Network Diagnostics
If you use a proxy server…
Check your proxy settings or contact your network administrator to make sure the proxy server is working. If you don't believe you should be using a proxy server: Go to the Main menu > Settings > Change proxy settings… > LAN Settings and deselect "Use a proxy server for your LAN".