Connected or not...?!

A few days back, my wife experienced a weird network issue on her laptop. Usually the laptop receives an IP address immediately on start-up, but this day she received the following network error message: "Limited or no connectivity." What does limited connectivity mean, is there a connection or not? The message did not say anything about the origin of this.

At first I told her to repair the connection to renew the IP address. This has helped in the past. But no luck this time. I then consulted my wireless router to see if there should be anything that could hint a solution. In the device list I could see the correct MAC address, but there were no IP address related to that MAC address. Everytime a repair was attempted the device left the list and came back with no IP address. I reviewed the security settings to see if the wireless filter was messing up things or the DHCP was not working properly.

Well, GIYF (Google Is You Friend), so I started hunting a solution. One solution was that malware had replaced the tcpip.sys file. My tcpip.sys file seemed in fine form. Just to be sure I made a full computer scan with AVG, no luck. I then uninstalled the network driver, and re-installed the latest version. This neither solved the issue. After reading several forum posts I realized that this issue is related to Windows XP Service Pack 2, and the Microsoft patch (KB884020) should do the work. Again, no luck, this patch only seems to work with a specific language version of Windows XP. Another hint I got was to use the Winsock XP Fix, but unfortunately this neither solved the problem. At this point frustration started creeping in on me.

Another hint sent me check out which services there where running (services.msc from command line). I then realized that the DHCP Client was not running. Trying to start it manually gave me an error saying that a dependent service could not be started. Checking the Dependencies tab under the DHCP Client Properties reviled an unknown service. These services should be removed through the registry. I navigated to the following keys in the registry:


For each of these, on the right side, double-click: DependOnService
I then deleted SYMTD. In the post where I read this, it also said that it could have NISDRV instead. I was now able to start the DHCP Client service again. After a reboot, the laptop was able to receive an IP address.
So what is this SYMTDI? The SYMTDI service appears to get installed by Norton Antivirus, where it is added as a dependency for DHCP client. The unistall of Norton removes the file: C:\WIndows\System32\Drivers\SYMTDI.SYS, but it does NOT remove the entry for SYMTDI in the DependOnService value for DHCP. So, SYMTDI won't start because symtdi.sys has been removed. I had actually uninstalled Norten Antivirus just before I ran into this issue.

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