Error 651 is a well-known bug in Windows 7 which happen when you try to connect to the Internet using PPPoE connection
Way to fix error 651 Windows 7 is to replace raspppoe.sys
You can download the raspppoe.sys file from one of the below links,
- Go to windows explorer or My Computer.
- Open your system drive. (Most of the times its C:\)
- Double click on the Windows Folder.
- Now double click on System 32 Folder.
- Then go to Drivers folder.
- Rename raspppoe.sys file to old_raspppoe.sys.
- The copy the downloaded raspppoe.sys file in to this folder.
- Now you may restart your computer enjoy the internet.