Hi I found a bug report that says this was fixed in July of this year by blocking a file called '''protector64.dll''' from connecting to Firefox. This was done because this file was causing a huge amount of crashes for Firefox users. It looks like comes from a security software or endpoint protection software from a company called Morphisec. You can try to find this software on your computer & disable it. And maybe report to the company that their software is causing crashes on Udemy while trying to watch a simple video. I'm still surprised this file was able to connect to Firefox since the bug report says it was blocked from connecting. I'll ask if anyone can investigate if the DLL file updated itself to get around the block. [https://bugzilla.mozilla.org/show_bug.cgi?id=1896442 Bug 1896442 - Crash in [@ protector64.dll | <unknown in ntdll.pdb>] I think name of the software you have is called Morphisec for Windows Endpoints. https://www.morphisec.com/products/morphisec-windows-endpoint-protection These "endpoint" software programs are very aggressive in blocking anything that might even look like a threat. Even things that aren't really a threat. So innocent things will get blocked from time to time then cause a crash.