Looking for assistance please!

I have Norton AntiVirus 360 (version 22.5.2.15) on a Vista platform.  I use MS Windows Mail 2011 for emails installed on my PC.  (Prior to Windows Mail 2011 I used Outlook which I am still able to access online but isn't ideal as my email storage folders are only 'complete' on my PC).

I am finding that I am getting time out messages when trying to update my email inbox such as "Your server has unexpectedly terminated the connection.  Possible causes include server problems, network problems, or a long period of inactivity".

In addition when opening emails from my PC, the screen jumps from the email screen to my Internet supplier screen (Mozilla Firefox).   I then have to go back to the email screen to view the email.

Also unable to move messages to the storage folders without them jumping back to the inbox.

I have changed the Server Timeout setting from 2 mins to 5 mins (longest time available) but it hasn't made any difference.

My incoming mail server is IMAP with the server settings:  incoming:     imap-mail.outlook.com  and outgoing:     smtp-mail.outlook.com
Server Ports:  Outgoing mail 587   and incoming mail 993

I am not techie minded but wondered if it is the antivirus that is terminating the connection?

Can anyone advise me please and provide a solution!

Frustrated!!!