We have an application that uses the LogonUserW method in advapi32.dll to authenticate a user/password against a domain. We have been successfully using this methodology for several years, but recently the LogonUserW method call is failing if the user does not have admin rights. This behavior seems to correspond with a recent Windows patch that was installed. We have rolled back the latest patches and the method call now works as it did previously. Looking for answers to explain what could have happened and if there is a way to get around it.