You're not alone -- my domain has been experiencing similar issues for the past 36 hours or so. The webmail panel gives a high volume of IMAP connection dropped errors, and POP mail retrieval is asking to re-enter passwords on the majority of retrieval attempts.
This is happening even on (amongst other accounts) my own main account, an account that has been around for a number of years, now -- so it's not a new account set-up issue. Nor have I made any changes to mail account configurations in...longer than I can even remember.
It happens on both WinXP and MacOSX 10.4, in different email clients, different browsers, over different ISPs, you-name-it-I've-tried-testing-it. I think this is pretty clearly a problem on the hosting side, and have accordingly filed a detailed support request. If you haven't done likewise, and are still having the problem, you might consider filing a support request of your own, to help bump the issue up on the DH priority list.