About once a day, my latest Firefox x64 (under latest Win x64) stops being able to load content in new tabs. Content in existing tabs continues working. I usually have 15-50 tabs open, but I haven't been able to connect the problem to any particular action/state in/on my Firefox instance. My Chrome (which I also always have open) doesn't have this problem. My PC's internet access, in general, continues to function normally, i.e. I haven't been able to detect any other problems which "happen at the same time." My cybersecurity tools include (paid) Kaspersky Internet Security, (paid) MBAM, and a SentinelOne agent. This problem started happening maybe 3mo ago, and has continued across several Firefox updates (and several Patch Tuesdays / Windows restarts). Restarting Firefox always solves this problem (until the problem next recurs), so it's not, you know, catastrophic, but it seems like it might be something you want to know / do something about. Let me know if/when/what further diagnostic information I could provide.