I am using TB 45.4.0 on both a PC (running windows 7) and a Macbook Air (running El Captain 10.11.6). My email account is set up as IMAP. I have an Archive folder where I put all the emails I have received in the last couple of months. It's a pretty big folder (about 5,000 emails). Starting about a week ago, whenever I would try to look at that folder on the Mac, I would get the following message: "Server has disconnected. The server may have g..." (For some reason, that's all I can see of the message on the Mac before it disappears.) While I can see the headers of those 5,000 emails in the Archive folder, I cannot view any of the messages. I am *not* getting this message on my PC - all the emails in the Archive folder can be seen and read. I spoke with my ISP but we were unable to solve the problem. I am not having this problem with any of my other folders, just this one. Any thoughts on how to diagnose this? Thanks for your help.