Step 1: Use the Internet Connection troubleshooter
a. Open the Internet Connections troubleshooter by clicking the Start button, and then clicking Control Panel.
b. In the search box, type troubleshooter, and then click Troubleshooting. Click View all, and then click Internet Connection troubleshooter.
Step 2: Try disabling your anti-virus software and then try to establish the connection
http://windows.microsoft.com/en-US/windows7/Disable-antivirus-software
Note:Running the computer without firewall or the anti-virus software is a potential threat to the computer; make sure to enable the security software after completing the troubleshooting steps and after identifying the issue.
Step 3: Check your Internet Service Provider
I would ask you to check if your Internet Service Provider has any suggestions with this issue.
Hope this information is helpful and let me know if you need any further assistance.
