Intermittent problem downloading BT Yahoo messages on Windows Live Mail 2012

It downloads them maybe once or twice a day but never when I manually click to receive. I get following error messages:

Server Error: 0x800CCC90
Server Response: -ERR inactivity timeout
Server: 'mail.btinternet.com'
Windows Live Mail Error ID: 0x800420CD
Protocol: POP3
Port: 110
Secure(SSL): No

Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems or a long period of inactivity.

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

Have tried Essentials Repair and have disabled email scanning in anti-virus software - makes no difference.

BT says it's not their problem (but then they would...)

Any suggestions appreciated

(Do not want to delete email account and re-add as I don't want to have to separate thousand of emails back into folders)