No it's not the router!!
It DOES NOT matter that other things work. We have seen this issue time and time again. Sometimes the router has new firmware but looking over this post those details are missing.
Sorry but trying another router is just not an option when I have a router that works well with all my other computers - it has nothing to do with the firmware - the issue lies in the AMP. Nothing else is effected and the only thing that does not work is the AMP in that it refuses to find the wifi network when the security is on (and that has always been on).
As I said it started wiht the latest download 10.7.2. Please forget router issues -it is sound.