Possible MacBook Pro Wireless Connection Fix

from here:

If this did not work, try the following solution. It worked for me to some extent on another computer. The only extra thing I need to do is always choose my wireless from a list every time the computer wakes up. Just slightly annoying, but takes less than 10 seconds total from the time you wake up the computer.

Solution: Launch the “KeyChain Access” application. Select “Passwords” on the left navigation area under “Category”. Then in the search box on the top right, enter the SSID of your wireless network. In my case, I typed “wide”. You will see two or four entries where the name is your SSID. Delete all the entries. The next time you connect, it will re-create the necessary records. This might solve your issue.