I have a user who is complaining that when using IE7, his sessions will close and return him to the login page several times a day, while he is in the middle of working in Zimbra (composing a message or working with files in the briefcase). He uses the "detach message" feature a lot, and told me that he might have 3-4 messages in process and detached at any one time. He also complains that sometimes the browser closes on him completely.
I searched through a bunch of Bugzilla bugs and haven't found anything related yet. Are any other admins seeing this issue?