Windows Live Mail Version 2012 (Build 16.4.3528.0331) with Windows 7.

Messages were being received and sent successfully up to 22 Jan using my POP3 email account (Virgin though still using ntlworld.com).  Since 23 Jan sending has been failing with no changes having been made to Properties.  Messages continue to be received OK.  Sequence:  Connection succeeds and then Authorization fails.  Although the ERROR word comes up on the bottom bar of the screen there is no explanatory error detail message in the Tasks/Error window, only a blank screen.  I have checked all the Properties fields and all are the same as before when sending was happening successfully.  Which piece of the Authorization could possibly be erroring when I've not changed anything?  Thanks in anticipation of advice and assistance from good citizens.