Hi,
Have you made any changes to your computer prior to this issue?
You may follow the suggestions and check.
Method 1
You may follow the steps from the article.
How do I fix network adapter problems?
http://windows.microsoft.com/en-US/windows7/How-do-I-fix-network-adapter-problems
Method 2
Let’s try to reset WINSOCK, IPv4 TCP/IP and IPv6 TCP/IP stack.
a. Click on Start and in the search box, type cmd.
b. Right click on the Command Prompt, select "Run as Administrator" to open a Command Prompt.
c. At the command prompt window, type the following commands:
netsh winsock reset catalog that resets WINSOCK entries to installation defaults.
netsh int ipv4 reset reset.log that resets IPv4 TCP/IP stack to installation defaults.
netsh int ipv6 reset reset.log resets IPv6 TCP/IP stack to installation defaults.
d. Restart the computer.
Try Changing TCP/IP settings. You may try the steps listed in the below link:
Change TCP/IP setting
http://windows.microsoft.com/en-US/windows7/Change-TCP-IP-settings
Method 3
Check if the issue exists in a clean boot state.
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7
http://support.microsoft.com/kb/929135
Note : After troubleshooting follow Step 7: Reset the computer to start as usual ****
Method 4
Temporary disable anti-virus and check.
Disable anti-virus software
http://windows.microsoft.com/en-US/windows7/Disable-antivirus-software
Note : Antivirus software can help protect your computer against viruses and other security threats. In most cases, you should not disable your antivirus software. If you do have to temporarily disable it to install other software, you should re-enable it as soon as you're done. If you are connected to the Internet or a network during the time your antivirus software is disabled, your computer is vulnerable to attacks.