If you have tried all the previous steps and are still viewing the Page Cannot Be Displayed message, it might be caused by a problematic Internet Explorer add-on. An add-on is a program you install that connects itself to Internet Explorer. Some common add-ons are toolbars, such as Google or Yahoo. Sites that require ActiveX controls when viewing may also install add-ons. For the most part, IE add-ons are safe. A damaged or otherwise problematic add-on, however, can cause the Page Cannot Be Displayed error.
To find out if an add-on is causing the issue, close all instances of Internet Explorer. Go to the Start menu and point to All Programs. Point to Accessories and then System Tools. Select Internet Explorer (No Add-ons). If you are using Windows Vista, you can simply go to the Start menu, type "Internet" into the Start Search field and select Internet Explorer (No Add-ons) from the Programs list. An Internet Explorer window will open without add-ons.

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Enter a website address and press
Enter. If the website appears without the Page Cannot Be Displayed error message, close the IE window. Open Internet Explorer normally and turn off all add-ons by going to the
Tools menu, pointing to
Manage Add-ons and clicking
Enable or Disable Add-ons.

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Click on each add-on and then click the
Disable button. When all add-ons are disabled, continue working in Internet Explorer. Enable the first add-on in the list and continue working in IE. Gradually enable each add-on one at a time until you find the problematic one. Disable or uninstall that add-on.
Learn more about ActiveX controls in Internet Explorer by reading Internet Explorer Security Settings - ActiveX Controls. Trying to install the newest version of IE but having problems? Check out Internet Explorer 8 Won't Open or Can't be Installed.