On launching, Thunderbird used to display the folder that was being displayed when it was last exited. Then, from sometime in the last week, Thunderbird now only launches displaying the same subfolder. If I change folder and exit, it does not remember that. Instead, it launches showing the same subfolder. I have no extra tabs open. I do not use cccleaner or any other tidying up tools. I have no add-ons other than what came with Thunderbird. It's completely vanilla. I do not use unified inbox either. Without giving away any names, the subfolder is /myaccount/Received/subfolder77. So it isn't a subfolder of inbox or anything, but it isn't under Local Folders either. I have tried an number of suggestions: Account Settings > Server Settings > Check for new messages at startup is checked; as it always was. Options > General > Thunderbird Start Page is unchecked I cannot make it revert to the previous behaviour. To get round this issue, I wouldn't mind if I could force it to the inbox on startup, but the only add-on that did that has been withdrawn by the author. I would be grateful for any ideas. Kindest Regards Ian P.S. I also notice that Thunderbird is not checking for new messages on launch, so it looks like this might be another symptom of whatever problem is causing this.