Please ensure that your copy of Windows is completely up-to-date, and that you have all released patches. You can always attempt to uninstall and reinstall software that is having issues.
Check with Microsoft for specific help on this issue, perhaps their FAQ database?
Unless it is being caused by a virus or spyware, this isn't the appropriate area.
Good Luck
PS: Some infections modify what's known as a "HOSTS" File.
These files control what sites can or cannot be viewed by your computer.
Open this file, and remove any lines containing the URL that may be being blocked.