Came across this and found it useful, so I thought I'd post up a current working implementation of it since RunAsSet has gone away. MsgBox (0, "", _ValidUserPass ("Username", "Domain", "Password")) Func _ValidUserPass($username, $computer, $password) Local $valid = True RunAs($username, $computer, $password, 0, @ComSpec & " /c echo test", @SystemDir, @SW_Hide) If @error Then $valid = False Return $valid EndFunc