Archive for January, 2007

ndis.sys driver_irql_not_less_or_equal blue screen (bsod) after installing Virtual PC and booting up with network cable plugged in

Ever since Microsoft began offering Virtual PC for free to download, a lot of users have been installing it to test out the usefulness of virtual machines. A couple laptop users complained that their machines would blue screen while starting up Windows with the wired network cable plugged in, although Windows would start up fine with the cable unplugged (which could then be plugged back in after login). I couldn’t figure it out but did narrow it down to Virtual PC 2004 being installed. I finally had the chance to work on one of these laptops for longer than five minutes and began my search on Google for the answer since I sure couldn’t do it myself.

All of my searches for a combination of the words “virtual pc ndis.sys blue screen driver_irql_not_less_or_equal” came up with irrelevant results. The only page that came close was this newsgroup post that suggested that there was a conflict between Virtual PC and the VPN client (Nortel Contivity VPN) installed on the laptop. So I went off searching for more details about the conflict and found this page that suggested uninstalling both Virtual PC and the VPN client, then reinstalling Virtual PC first before reinstalling the VPN client.

Well, first I uninstalled the VPN client and tested to see if the problem really went away. It did. I noticed that version 5.x of the client was installed so I tried installing 6.x. The problem came back. Uninstalled VPN, uninstalled Virtual PC, rebooted, reinstalled Virtual PC, rebooted, reinstalled VPN, rebooted, blue screen.

I decided to see why these two software would conflict. I went to Control Panel, Network Connections, opened the properties of the wired connection and examined the list of services and protocols enabled for the connection. The ones of note were the network filter services: Virtual Machine Network Services (from Virtual PC), Eacfilt (from VPN client), and Odyssey Network Services (from Funk Odyssey wireless client software). I unchecked the Virtual PC service from the adapter, rebooted, and everything was fine except that the adapter was no longer available for use within Virtual PC.

Back to the services list, I couldn’t uncheck the VPN service since the user would need it on this adapter but I wondered why the Odyssey service was enabled on the wired adapter. I rechecked the Virtual PC service and unchecked the wireless service. Rebooted and everything was fine! Checked to make sure Odyssey was working with the wireless adapter, checked to make sure Virtual PC worked with both adapters, and checked to make sure VPN worked with both adapters. Success!

Summary: If you’re getting the same type of blue screen from NDIS.SYS that I observed, check your list of services enabled for the wired adapter and disable any unnecessary services. Good luck!

2 comments January 5th, 2007 at 03:04pm


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