How to Fix Master Browser (MRxSmb) Event ID 8003 errors

I was reviewing some Windows Small Business Server 2003 Event Logs and came across a repeated entry in the System log. It basically looked like this:

Event Type: Error
Event Source: MRxSmb
Event Category: None
Event ID: 8003
Date: 5/8/2007
Time: 10:05:16 PM
User: N/A
Computer: [SERVER]
Description:
The master browser has received a server announcement from the computer [computer] that believes that it is the master browser for the domain on transport NetBT_Tcpip_{#######-####-####-#. The master browser is stopping or an election is being forced.

It took quite a while to find a solution, and even those were buried in forums or other posts. So I decided I would post the things that I believe can help. Here are some steps you can follow (no guarantee that they will work, but it worked for me and for others based on the various things that I read).

1. Look at the System Event log on your Server and look for the Error 8003 (like the one listed above). Within that log, identify the “computer” that is announcing itself as a master browser.
2. Go on to the computer identified in step 1 and go to the Services Administration panel. You can usually find this by going to Control Panel > Administrative Tools > Services.
3. Once you have Services open, look for an entry called “Computer Browser”. If that Service is “started,” you have found your culprit. If not, you may have to try the registry hack listed in step 6 a few steps
4. Double click on the “Computer Browser” service to edit it. STOP the service and then change the type to Disabled (from either Manual or Automatic). Click OK to apply your changes.
5. That should have resolved the issue. You should check your main servers event logs periodically to be sure that the error doesn’t show up. If it continues to show…
6. …you have to check the registry value on the computer. You do this by launching your registry editor and going to the following key:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Browser\Parameters\IsDomainMaster
   and ensure that it is set to FALSE. If it isn’t, you can change it to FALSE. Caution: registry edits are dangerous so only do this if you are sure you know what you are doing and the previous fix didn’t work. You probably have to reboot the machine to make the change take place.

I have also read that you need to be sure that all of your computers should be on the same subnet. If the above doesn’t work, be sure to check that.

More detail on the Computer Browser Service can be read here at Microsoft.

Steps 1-5 worked for me. I hope that this was a useful tip (given that it is so hard to find the solution). If it is and it worked for you, drop me a comment. If it didn’t work, I would still like to know.

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