Intermittent OS-X Error Message "Mail can't connect to the account"

Every few weeks when my computer is just sitting there I get an error message "Mail Can't connect to the account" and "Enter the password". The password is already filled in (and replaced with stars). Clicking "enter" doesn't usually help. Later the problem goes away.

I think the MAC is checking the POP mail server every few minutes like it is supposed to, and the COX POP mail server is rejecting the connection. Since the problem goes away without my changing anything, I think the POP mail server is having intermittent problems verifying my userid/password. 

I have seen similar problems on other systems at work, and it turned out to be intermittent problems with the POP server contacting the centralized server containing the database of userid/passwords. 

Has anyone else seen this set of symptoms?

bryan