I use Thunderbird and Chrome within Sandboxie (SB). I have Win 10 Pro. Up till a few weeks ago, I could open Thunderbird email links as follows: (1) If Thunderbird was non-SB, the link opened in non-SB Chrome. (2) If Thunderbird was within SB, the link opened in SB Chrome. Now, I can still open links as in (1). But if I try to open a link as in (2), I get the following message: - This file does not have an app associated with it for performing this action. Please install an app..... Because I can open links that are not within SB, I completely uninstalled SB (after making a note of any of my non-defaults in "Settings"). I then re-installed SB. The same error message appeared when I clicked a Thunderbird link. I would be grateful for any advice on how to open Thunderbird links from within SB.