You try to initiate the dialer in Windows 7 and only found that it doesn’t work and returned with an Error 651: Your modem (or other connecting device) has reported an error. You had tried to restart your PC, your router, your modem etc. and the problem doesn’t go away.
The Possible Solutions
It is not hard to find that there are a number of users encounter this issue on the internet, but surprisingly this error bugs some of the Windows 7 (Beta or even RTM) users and it seems that there is actually no official solution for it.
There are, however, a lot of workarounds, suggested, of course, by other users. If you have this problem in Windows 7 (or may be Windows Vista/XP as some of the solutions works on these operating systems, too), check out what I have found for the possible solutions for this error:
1. Replace the raspppoe.sys in Windows/System32/Drivers directory. (High Risk!) source
Some of the users claimed that by replacing the raspppoe.sys in Windows 7 with the Vista one seems to be able to solve the problem.
I have tried this previously when I was bugged by this error, but it didn’t help with the issue and created another error: Error 797. This workaround most likely works on a PC with Windows 7, that had the Error 651 initially.
Though, I will not suggest a replacement of this system file as it might cause even more problems if you doesn’t handle it well. However, if you insist of trying your luck, go ahead. If you have problems replacing or renaming due to an error with the TrustedInstaller, check out this link. Take over the ownership of the file and replace it with the Vista one.
Quoted from Windows Reference.com:
The RAS PPPoE driver file “raspppoe.sys” found under c:\windows\system32\drivers folder seems to be the root cause of the problem. Fortunately, we can workaround the problem simply by renaming the original raspppoe.sys file to something like “raspppoe_orig.sys” copying a working file from a Windows Vista system. If you do not have access to a Windows Vista system. click here to download raspppoe.sys file (unzip).
2. Windows System Restore
Some of the users report using a Windows System Restore point from an earlier date could solve the issue, especially if you have any software updated/installed to your PC that caused this error. Possibly one of the best solutions out there.
3. Uninstall Microsoft Virtual PC 2007
In the replies on a windowsreference.com page, some users suggested that by uninstalling Microsoft Virtual PC 2007, the problem seems to be fixed. Previously I uninstalled my Virtual PC, which comes with Windows XP mode for Windows 7, but it didn’t solve the problem as well. If you have Microsoft Virtual PC 2007 installed, go ahead uninstall it and see if the problem goes away for you.
4. Disable IPv6 for your connection source
I also found that some users claim that by turning the IPv6 off for your dialer, the problem can be solved.
5. Uninstall modem source
If you have a dial up modem in your computer but don’t use it, you can disable it as this may help with the issue.
6. Disable Windows Vista/7 auto-tuning feature source
One user suggests that the auto-tuning in Windows Vista/7 has malfunctioned and he suggested a workaround to disable it prior to firmware upgrade for your router. This seems promising for the user who is using a router for the internet connection.
7. Disable some special function of your LAN card source
A user over at Technet who had the same problem as mine has tried to turn off some special features on their LAN card such as Interrupt Moderation etc. and it seems able to solve the problem.
8. Reinstall LAN/NIC drivers
This is one of the most common suggestions by the community but it didn’t work for me as both of my LAN card are functioning well.
9. Reinstall networking in Windows Vista/7 source
Some say that by reinstalling networking in Windows seems to make the problem go away.
10. Perform clean boot source
A moderator over at Technet suggested to a user to perform clean boot to find the root of cause, and replace the raspppoe.sys file as well.
11. Uninstall Sun’s Virtual Box
One of the replies says that they solved the problem by uninstalling Sun’s Virtual Box, along with Microsoft Virtual PC. I am not sure but perhaps there might be some conflict between the virtual network driver with the real one. You can give it a try if you had any virtualization software installed in your PC.
12. Recreate Dialer and restart the ADSL modem/router
This perhaps works if the error occurs when something hung during the connection. Remove the dialer and create a new one, then restart your PC. Turn off the ADSL modem/router, wait for more than 30 seconds, then turn it on. Then try to connect.
13. Avoid sudden connection interruption by software (preventive method)
This is from my own experience, I not sure how and why, but it just meant for sharing. One day, I had my connection up, and I installed Norton Internet Security without disconnecting the broadband. As usual, a Internet Security Suite will have bunches of modules to protect your PC through networking security, so I did some necessary network scanning with it without turning my broadband off. Then all of the sudden, my broadband disconnected and when I tried to reconnect, error 651 occurred again. Fortunately it doesn’t persist as I managed to connect after waiting for a few minutes without doing anything, so I have learned that if you somehow know software is going to interrupt your dial-up internet connection, disconnect your connection first before proceeding.
14. Call your ISP (Internet Service Provider) for help
If you still unable to resolve the issue, try to contact your ISP customer service for help. It’s probable, the problem is caused at their end, so it can be solved by them.
Before you run any of these changes, make a backup. The best form of backup is a system restore or backing up files you replace.
It’s apparent that there are a lot of Windows users have been bugged by this error, and I really hope this article is able to help to solve your problem. Even the Technet forum thread about this error marked this whole list of possible solutions as a solution, which means that there is no official solution for it. But please be reminded that all the solutions were gathered from the internet, such as article, forum etc., and I can’t guarantee that which one/how they will work for you. If they did, you are always welcome to comment and let others know what have you done to solve your problem. Else, I am sorry that I couldn’t help you, perhaps you can ask for help from your ISP. I will update several more possible solutions based on the readers’ replies. Good luck!