I keep getting this error in Firefox; what is the problem?

I keep getting the following error when trying to view some pages. Other pages load just fine. Also get same error on same pages in IE, so it’s not Firefox. What is going on? It is driving me crazy.

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The connection was reset

The connection to the server was reset while the page was loading.

* The site could be temporarily unavailable or too busy. Try again in a few
moments.

* If you are unable to load any pages, check your computer’s network
connection.

* If your computer or network is protected by a firewall or proxy, make sure
that Firefox is permitted to access the Web.