After restarting the RAS services I started to troubleshoot.

I tried everything from disabling/enabling the Miniport driver to deleting the PPTP config and starting again – all to no avail.

Running the Microsoft Port Query tool (http://support.microsoft.com/default.aspx?scid=kb;en-us;310099) I found that the PPTP port 1723 was “ESTABLISHED” – this should be in “LISTENING” mode. This tells me that there is something running on the 1723 port that shouldn’t be – locking my users out.

I then used another great tool from sysinternals to find the process that was using my PPTP port. The tool is called TCPView and you can download it at http://technet.microsoft.com/en-us/sysinternals/bb897437.aspx. TCPView told me that the connection on port 1723 was established by my SQL server and the exe that was using it was a BlackBerry service. I killed the process, restarted the RAS services and our PPTP VPN was now working.

Users were reporting that the PPTP VPN was no longer available. Checking the logs I found nothing out of place (Routing and RAS was started and the snap-in didn’t report any issues). I rolled back the Windows Updates and the PPTP became active.

I’ve just attempted to install the v2 update to the KB article and the same problems occur. Do not install this update!

There is an “official” MS blog post however there is nothing noting the PPTP issues that occurred for me. I actually posted a comment with my particular situation on the comments page – however they haven’t approved the comment. http://blogs.technet.com/sbs/archive/2008/07/09/hold-off-on-installing-hotfix-948110-on-sbs-2003-servers.aspx

Microsoft’s KB article didn’t uncover any reasons why my PPTP connectinos failed – http://support.microsoft.com/kb/948110