Just last week, similar or same. had to tell windows to forget all prior connections and then make a fresh connection.
I am running high speed dsl. wi-fi router on my main windows 8 dell computer. When i log on my dell lap top. I have to troubleshoot problem with connection. It says wireless network connection doesn't have valid ip confriguration. I click on problem and it fixes. But i have to do every time i log in on my laptop?