WLAN problems after Windows Update

I’ve been seeing a problem lately with a few computers. After installing the latest security updates, their WLAN card stops working. It is unable to acquire a dynamic IP address from any router, and setting a static IP address does not work either.

The cause
The cause of the problem is a Microsoft recommended hotfix, (815485). The hotfix is part of an optional, though recommended update to Windows XP.

The solution
Resolving this problem can be done in one out of two ways, either by uninstalling the specific hotfix, or by rolling back to a previous system restore point.

Uninstalling the hotfix:

  1. Go to the Control Panel and open the entry “Add or remove programs”
  2. Scroll to the bottom and look out for an entry called Windows XP Hotfix (SP2)Q815485
  3. Remove the entry

The other solution hinges on System Restore being active on your computer. If it is, simply follow the instructions (given here) from Microsoft to roll back to a restore point from before the problem occurred.





6 responses to “WLAN problems after Windows Update”

  1. Anonymous


    I’m currently having this problem after installing WIN XP SP3. Tried to look for the hotfix 851485 as you advised, but unfortunately it does not even exist on the microsoft site.

    Did you give the correct hotfix reference.

    Thanks in advance.

  2. Aleksander R. Rødner

    I’m certain the name is correct. The full hotfix name is “Windows XP Hotfix (SP2)Q815485”. I’ve updated the post with a link to the download page for the hotfix.

    KB Article: http://support.microsoft.com/?kbid=815485
    Download page:http://www.microsoft.com/DOWNLOADS/details.aspx?FamilyID=009d8425-ce2b-47a4-abec-274845dc9e91&displaylang=en

  3. Etienne

    Windows updated my system yesterday with SP3 and I am experiencing the same problem. My WLAN is not working and I am unable to find the hotfix 851485. Microsoft has really screwed me up!

  4. Aleksander R. Rødner

    Etienne: the hotfix is part of the Service pack. If you are experiencing problems, I strongly recommend a roll-back and a reinstall of SP3.

  5. Etienne

    Thanks Aleks, I just restored my system to earlier today when I still had my WLAN working. I now have WLAN working fine again. What if Windows Update does the same download again. Will the same not happen again because we can’t control what is automatically updated.

  6. Aleksander R. Rødner

    Etienne: There’s no guarantees that you won’t encounter the problem again, so you should really just try it, and if it doesn’t work, don’t worry about it.

    Anyway, in my opinion, SP3 is not as important as SP2, and it has some flaws, like this one, that means it hasn’t been as widely implemented.

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