New logic board and network connection problems

My late 2007 MBP just had a new logic board installed. I have home and work wireless networks that are configured to connect automatically. This always worked flawlessly in the past. My MBP would find the network, connect and all was well. Since I've had the new logic board I'm having issues. The wireless network will be detected but an IP address is not assigned so I can't get on the network or internet. Both my home and work networks were set to assign a specific IP address to my computer. The MAC address detected by the router is correct, at least according to System Preferences.

The only way I can connect is to disable the firewall (Allow all incoming connections). When I do this I connect immediately to the network and everything works as normal. I can even turn the firewall back on and everything will be fine, that is until I leave work and turn the computer on at home. Then I have to go through this again. And then again when I go to work in the morning. I've tried deleting my router profile and resetting from scratch, deleting the network profiles in System Preferences and re-detecting. I don't know what else to try. It's an annoying problem.

Any suggestions?

Thanks.
Kevin