I am having this problem across multiple wifi attachments. I can use the internet for an hour or two and then a reauthentication is forced on me but the password is not accepted and I then must restart just to keep using the internet.
I have been using a tp-link tl-wn722n, but this happens with an edimax i own as well.
Three months I've been trying to solve this with odd answers I find, no luck.
