Unable to download files from Internet Explorer

My computer suddenly froze while trying to access my mails and download a .doc and .ppt file attachment. I cannot open or download anything from any site and always have the error below when doing it. Is this some sort of a bug or malicious threat? Please send some help. Thanks.

Windows Internet Explorer
Internet Explorer cannot download / from windows.
Internet Explorer was not able to open this Internet site. The requested site is either unavailable or cannot be found. Please try again later.
