Why doesn't my Macbook detect network after sleep? every time that my 2007 macbook with lion goes to sleep, either manually (closing the lid) or timing out, i have to restart my computer to connect to the wireless network.  It fails to detect any networks at all until I restart, then it connects to my default network no problem.  What can I do?
Clear the network out and re-setup it.

Otherwise, I've run into this issue before, what brand of router are you using? And does it happen with other networks apart from this one? 

Related: Why doesn't Airport reconnect after sleep or shutdown?