I am receiving the following message:-

Unable to send or receive messages for the o2.co (val.gas) account. Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems or a long period of inactivity.

Server: 'mail.o2.co.uk'
Windows Live Mail Error ID: 0x800CCC0F
Protocol: POP3
Port: 110
Secure(SSL): No

How can I rectify this?  It worked perfectly yesterday.

[Original title: Windows Live Mail]