You might refresh your DNS, check to see if your system is running through a proxy (network settings in IE Options)...I've seen infected PC's end up on a proxy unbeknownst to them that caused similar issues. Is it a site you normally visit?
Run a malware scan, MBAM is a good place to start (Malwarebytes).
Have you tried a different browser and achieved the same result?
You could always temporarily manually change your NIC's DNS to 8.8.8.8 (Google's DNS) to see if it is at all related to that.
What browser are you using? DNS is usually one of the top things to look at when issues occur where you can't successfully browse the web...I stopped using my ISP's DNS years ago because of inconsistency on their end, I used Google for a while and now I primarily use OpenDNS for filtering and then Google DNS as a backup. You can go to OpenDNS and use their servers for free, or sign up for a free home account.
Might be worth trying, might not solve a thing. First things I would try are another browser, malware scan, and dns change.
Hope that helps!