I had the same problem and I was always back to square zero each time I restarted my laptop. Here is how I fixed it windows 8 and should work for windows 7 as well.
1. Right click the wireless sign at the task bar, then select "Network and Sharing Center."
2. Select "Set up a new connection or network" below Change your networking settings.
3. Chose a connection option, choose "Manually connect to a wireless network, connect to a hidden network or create a new wireless profile" and click next.
4. Net work name: The same network name that you have.
Security type: Choose WPA2-personal
Encryption type: Choose AES
Security key: Enter the same password that you always use.
Tick the box "Start this connection automatically."
5...