MacBook Pro :: Connected To Wireless But No Internet / Email

I have a macbook pro that is running Mac OS X Lion. Recently, however, it stopped being able to connect to the internet through my home wireless network.  Nothing changed about my macbook or my network/modem/router.  Other devices in the house (PC, iphones) are able to connect to the internet via my wireless network, but not my macbook (and, incidentally, neither can my ipad now).  If I take my macbook to any other wireless network (coffee shops etc.) it connects to the wireless and I can access the internet without problem.  I have tried the online apple chat support feature, we tried a few things (can't remember what exactly) and have also had my internet service provider reset my modem.  Nothing has worked. 

I've tried various interventions suggested on some message boards here (restarting, resetting modem, deleting and reselecting airport etc.) and nothing has seemed to work.  Running network diagnostics comes up with nothing, and it states that there is nothing wrong with the wireless connection or the internet.  This is very frustrating, because I can't take it into an apple store (it will most definitely work on their wireless) and it doesn't appear to be related to my ISP (because of the other devices that are able to access the internet). There is something wrong with the communication between MY wireless network and the internet on my macbook.  

Info:
MacBook Pro, Mac OS X (10.7.5)