I just had to rebuild my system due to a hard drive crash. I was running Win7 Home Premium 64 bit and decided to do a clean install with Win7 Pro 64 bit to go to 32GB of memory (Microsoft doesn't allow a Win7 Home to Pro update). I installed Thunderbird version 38, which updated to 45.6.0. I've got a new issue since my rebuild. When I start Thunderbird, it downloads my new messages normally. The problem is that the program won't retrieve new messages If the program is open. Hitting F5 flashes the following message in the bottom activity bar "myname@myserver - There are no new messages on the server." even if there are messages. Hitting the "Get Messages" button does nothing at all. The "Check for new messages" setting is checked and set for 10 minutes, but doesn't work either, I verified the server settings, and the server name, port, and security settings are correct. I uninstalled Thunderbird, downloaded the current installer, and tried again. Same issue. Any thoughts?