[fetchmail]Error 2 and 7

I've been running fetchmail for a couple years without a hitch.  But lately
I have been seeing a lot of duplicate emails in my inbox.  A check of my
fetchmail errata shows a bunch of these:

   fetchmail: client/server synchronization error while fetching 
   fetchmail: Query status=7 (ERROR)

   fetchmail: socket error while fetching 
   fetchmail: Query status=2 (SOCKET)

Can anyone give me a clue as to how I might track down why this is
happening?

-- Bob Rankin