This has been a persistent problem for me. I first posted about it [https://support.mozilla.org/en-US/questions/1330028 here]. Since then problem has gotten progressively worse - the number of scenarios where the freeze happens has expanded and the frequency has increased. The gist of the problem is that Firefox freezes: a white transparent overlay appears over the window, the interface stops responding and no crash report is generated. When it happens: 1) When calling any sort of context menus and dialogs. It first began to happen when interacting with autofill menus for input forms, but now it happens with any context menu - input forms, file save dialogs, menus in the menu tab and even the right click context menu. 2) When opening new windows (notably NOT new tabs) such as when opening a private browsing window, bookmarks window, download history window or when using the picture-in-picture option on Youtube. How frequently it happens: The frequency appears to be random and not specific to any website. It used to happen after about an hour of browsing, but after I attempted a clean reinstall of the browser (see below) the frequency increased dramatically and I am now lucky to get half an hour of browsing before it restarts. What I've tried so far: 1) Looking for problematic extensions. Running Firefox in safe/troubleshooting mode seems to prevent the issue, so I started disabling extensions one by one. Ultimately though, even with all extensions disabled outside of safe mode, the issue persists. Reinstalling the browser without installing any extensions also does not resolve the issue, so any extension-related problems are seemingly ruled out. 2) Tracking memory and CPU usage. Nothing abnormal there - I have 16 GB of memory and Firefox rarely goes over 5. Just in case, I also increased the page file size on the main drive where Firefox is installed and enabled page files on all local drives (it was disabled for 3 out of 6 for some reason). This also didn't resolve the issue. 3) Refreshing Firefox. This did nothing except cause the 'Oops, there was a problem restoring your session' tab to first start appearing. Before the refresh that didn't used to happen at restart. 4) Disabling hardware acceleration. No effect. 5) Removing bookmarks. I had a very large number of bookmarks saved so I tried removing all of them. The issue persisted. 6) Deleting the places database. No effect. 7) Deleting the session restore files. This has been the most interesting option. Deleting the session restore files DID stop the freezing... until it came back again in a couple of days. Deleting the session files again after that did not make the issue go away again. 8) Doing a complete reinstall of the browser. I uninstalled Firefox from the Control Panel, then went into the AppData folder and manually removed any references to Firefox. After that I installed the latest version of the browser and refrained from syncing the new instance with my Firefox Account, or installing any extensions. Even with that, the issue persists. 9) Checked for hardware problems. Tests of RAM and the SSD on which Firefox is installed produced no errors. The issue also persisted through a GPU upgrade. Barring some arcane motherboard or CPU issue, I think hardware problems are ruled out - and it seems unlikely that a motherboard or CPU hardware issue would affect Firefox and only Firefox. Please help, this is an extremely frustrating problem and