Thanks again, jsher2000. I think I have determined the source of the problem, and it is not Firefox, or AVG, or the websites I have been viewing. It is Microsoft! Here's what I have observed: The websites were working fine last night, and earlier this morning. Then they were not. So, then I started to explore the problem using this forum. Along with following your great suggestions, I was seeing that there was no such problem in the Opera browser. After your last suggestion, and my screen captures, I decided to see what a restart of my laptop might yield. Once I decided to shut down and restart, I found that Microsoft had downloaded an update, and that it was being installed before my shutdown, and before the restart. After the lengthy restart, all of the affected websites are back in working order! Conjecture: While Microsoft was downloading the update(s), they turned off my antivirus protection without announcing doing so. Now that the update is installed, all is well. Thanks for your attention to my challenge. I will continue to come here for answers and support.