I'm getting these errors with Vivaldi 3.5.2115.87 and Sandboxie 5.46.4 classic (both x64) on Windows 4 x64 when I go to a page with videos (e. g. youtube.com, vimeo.com, etc.) and cannot use these pages! But Firefox x64 works. I also tested it with a new sandbox and get the additional error 1411 (unknown template=WindowsFontCache). Is it possible to delete this template from all sandboxes? I don't remember which sandboxie version i had installed before, but it didn't cause any problems. It might have been 5.43.6. Edit: I have now uninstalled 5.46.4 and installed 5.44.1 instead, which produces no error messages and works fine.