For maybe a month or two I have been seeing some strange behavior with Firefox closing after I close a downloaded file. Here are some examples. Lets say I am checking my email (yahoo) and receive a video file attachment. I launch the attachment which is set ot download and automatically open my player, which is VLC. VLC launches and plays as normal. When I finish, I close VLC and find that a few seconds later my Firefox window or tab also closes. This is not just with video files and not just from email. Same for doc files or pdf or jpg files. If it downloads and then I open it through Firefox, that tab closes once I close the third-party program. I also tried turning off the auto-launch and just download the files, but if I start them form the downloads display in Firefox the same issue occurs. If I start explorer and browse to downloads and just launch it from there then there are no such issues. I did notice that it only closes one tab, so if I have a dummy second tab, when the tab is closed I can use Ctrl+Shift+T to restore the previous window and continue, but it has gotten tedious to do that every time I download a file. I did check that neither Chrome of Edge do not have such behavior. System details. Firefox 103, Windows 10 21H2. No known major updates or changes have been made to the system to cause this change. The only extension I have is Ublock Origin, and I have tried disabling it but it did not help the problem.