Error 651 when trying to connect to the internet

Has this only started recently? Do you have McAfee? McAfee was updated at about the same time as the last batch of Windows 7 Updates and it is the cause of internet connection problems for most, if not all, McAfee users.

See this "critical" McAfee notice -

Some customers may experience a loss of network connectivity and/or errors in McAfee Security Center after a recent update

You should do the McAfee fix, if applicable. There are corresponding notices for their corporate products.

I've had to run the McAfee MCPR removal tool a few times before and it caused a licence problem if the PC was not connected to the internet during the removal. The McAfee support chat had to reset their records to allow reinstallation-reactivation. Here's their chat link - McAfee support - contains the link to chat

Hi,

1. Are you using a Wired or Wireless Connection?

2. When do you receive the 651 error message?

3. What was the recent hardware or software change made to the computer?

Please follow the links mentioned below to help troubleshoot the issue.

Method 1

Uninstall and reinstall the Modem and check if it helps.

Install or remove a modem

http://windows.microsoft.com/en-US/windows7/Install-or-remove-a-modem

Method 2

If Step 1 fails then, I would suggest you to reset TCP/IP and check if it helps.

How to reset Internet Protocol (TCP/IP)

http://support.microsoft.com/kb/299357

Method 3

Step 1

Make sure that you have the latest Windows 7 Modem drivers installed on the computer.

Update a driver for hardware that isn't working properly

http://windows.microsoft.com/en-us/windows7/Update-a-driver-for-hardware-that-isnt-working-properly

Step 2

Run this scan to fix corrupted system files.

How to use the System File Checker tool to troubleshoot missing or corrupted system files on Windows Vista or on Windows 7

http://support.microsoft.com/kb/929833

Also refer,

Troubleshooting Windows: Internet Browsing

http://support.microsoft.com/kb/316894

Hope this helps.