Internet Explorer will not Show Purchase

Internet Explorer 5.0 running 128 bit cipher rate will not show purchase or transaction type web pages, it says it cannot open the page. For example: I went to CompUSA and went all through the store but when I click on Checkout, it gives me the error above saying it cannot open the page, this is with any site featuring a purchase page. On Microsoft’s page, I went to no-charge technical support and the browser would not let me into that page, providing the same error. Any ideas anyone???