I've been having this issue on my Droid since Day 1, and was wondering if you've had similar experiences with your email (IMAP). I configured my Yahoo! email and am able to sync all my messages on 3G. However, as soon as the phone is on WiFi (work/home), the email gives an error messages: "Connection Error," or "Incorrect Username or Password." Switching back to 3G, the email syncs well. And switching back again to WiFi, the email doesn't sync. I got those error messages on 2 different phones. Any suggestions?