PPTP VPN Freezes System Upon Disconnect

[jminiman]

100% reproducible problem! Thinkpad T61 on XP SP3. Current version of Access Connections, Intel Wireless/LAN drivers, etc. I can login to my PPTP VPN server every time without any errors. However, every time I disconnect the VPN, Remote Connections freezes up and I can never re-establish any dial-up connection until I reboot. Ipconfig /release hangs, too. I've tried starting up using msconfig to disable all Thinkpad services and only have the most basic drivers started, and I still get the freeze every time I disconnect. VPN disconnect freeze happens regardless of whether I'm on my WiFi card or a Verizon datacard.

Has anyone seen this?

[jminiman]

I'd like to provide a little more detail. Looks like the callback notification just isn't taking place after I disconnect. Here is what I see:

[304] 16:10:39:562: PPPEMSG_Stop recvd

<...Stuff Here>

[3752] 16:10:40:843: RemoveFromTimerQ called portid=0,Id=10,Protocol=c021,EventType=0,fAuth=0

[3752] 16:10:40:843: FsmThisLayerFinished called for protocol = c021, port = 4

[3752] 16:10:40:843: FsmThisLayerFinished called for protocol = 80fd, port = 4: 0

[3752] 16:10:40:859: FsmThisLayerFinished called for protocol = 8021, port = 4: 0

[3752] 16:10:40:859: NotifyCaller(hPort=4, dwMsgId=10)

[3352] 16:10:40:953: PPPEMSG_LineDown recvd, hPort=4

[3752] 16:10:40:953: Line down event occurred on port 4

What I should see is:

[17892] 06-15 16:10:29:416: PPPEMSG_Stop recvd

<...Stuff>

[1480] 06-15 16:10:29:593: PPPEMSG_LineDown recvd, hPort=4

[1548] 06-15 16:10:29:593: Line down event occurred on port 4

[1548] 06-15 16:10:29:595: FsmDown event received for protocol c021 on port 4

[1548] 06-15 16:10:29:595: RemoveFromTimerQ called portid=0,Id=10,Protocol=c021,EventType=0,fAuth=0

[1548] 06-15 16:10:29:595: FsmReset called for protocol = c021, port = 4

<...Stuff>

[1548] 06-15 16:10:29:595: LcpEnd

[1548] 06-15 16:10:29:595: Post line down event occurred on port 4

[1548] 06-15 16:10:29:595: NotifyCaller(hPort=4, dwMsgId=23)

Why is everything hanging after line down event?

[jminiman]

Looks like I was able to fix this by forcefully uninstalling several duplicate network adapters (one of them being PPTP) via the registry. I changed the characteristic bit to allow uninstall, and then I just picked off the problematic network adapters in Device Manager. Although the adapters didn't seem to be causing any problems, all my freezing went away when I disabled the dupes. Glad I looked in there!

No more freezes now.