Recently changed from Pop3 to imap and keep getting this message. I receive mail OK but it keeps re-highlighting. I have changed the Server Timeout setting to the max of 5 minutes. Any solutions please.

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

This IMAP command could not be sent to the server before the connection was terminated.

Configuration:
   Account: tw
   Server: imap.1and1.co.uk
   User name: *** Email address is removed for privacy ***
   Protocol: IMAP
   Port: 143
   Secure(SSL): 0
   Code: 800ccc0f

Whenever I try to log into my hotmail account using a browser I get a server timeout after entering my user name and password.  This happens both with Mozilla and IE browsers, even after clearing cache and history on both.
I am running Outlook 2011 with a pop/smtp setup.  Sometimes Outlook will just stop receiving emails.  Whenever this happens I log into webmail and I have an email with a very large attachment.  If I delete the email Outlook starts working fine again.  When I had this problem in Outlook for Windows I could just increase the server timeout and it would download the emails.  I am trying to find a similar option in Outlook 2011.
Outlook has timeout errors connectng to a pop3 server continually, whilst mac mail, thunderbird and any other mail client I download has no trouble. 

Usual error is the old sever may be busy or high network load rubbish.

Especially if the pop3 server has more than 1000 msgs but not limited to this. 

I am ready to give up on Outlook and go back to Mac Mail (despite the inferior junk filter!)  Any ideas ?