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