So, I've had this issue with already 3 houses in the past week. I had been working perfectly with my MacAir for the entire time, then whenever i leave my computer to lock, the conexion is lost, and impossible to make it come back. It shows is connected, and everything is right but the connection does not work. Happened Monday at my boyfriends house, Wednesday at work and today at my house. Even tho I disconnect and connect the adapter it still, same with restarting the computer. I'm unable to connect it now to anywhere and i need it to work. Do i need to reset the adapter completely? Is it broken and need a new one? And in case you wondered, the router still works with other devices, that's whay i think is an adapter problem. 
Thanks in advance,

Laura