I can confirm that I am having the same problem with my Outlook freezing and intermittently not being able to logon, but I don't know how to fix it.
If you don't mind, I'd like to ask a few questions to try to isolate the problem.
What version are you using? I'm using 1.0-rc6.
Are you using SSL? If so, on all connections or just some (i.e. the remote ones)?
What are you using for authentication? PAM?
What is your dovecot server using for 'ioloop'?
What is your dovecot server using for 'notify'?
You can get those last two parameters from 'dovecot --build-options' (or something like that; I forget the exact verbage).
FYI, I've noticed that turning off the preview/reading pane reduces the number of timeouts, but it does not eliminate the problem. I do not know why this is the case. Perhaps you could try it and see if it helps you.
Joseph D. Wagner