Airport has a self assigned IP address and may not connect to the Internet

I own a Macbook with Mac OS Version 10.6.4. I was generally browsing and found that Firefox wouldn't connect to the internet. When I checked network settings, it said, "airport has a self assigned IP address and may not connect to the Internet". There is no single solution for this. You have to go through various steps to figure it out, like i did. It took me close to an hour to get my macbook to connect to the internet, so here goes :

1. Open System Preferences - Network. Make sure that Location: is set to Automatic. Click on Airport and then click on Advanced. Select the TCP/IP tab and make sure that Configure IPv4: is set to Using DHCP. If yes, click Renew DHCP Lease.

2. Try running Repair Permissions from Disk Utilities. Open Applications - Utilities - Disk Utilities, select your drive from the left pane and First Aid from the right pane. In First Aid window, select and run Repair Permissions. May not work but it is worth a shot.

3. The firewall might refuse inbound connections from the router. Delete the firewall configuration file, located at /Library/Preferences/com.apple.alf.plist and configure the firewall to temporarily allow all connections.

4. Disable the firewall on the mac. If you have another computer connected to the router, open the browser and access the web based setup page (Belkin, Linksys). Change your SSID, restart your router. Try and connect to your mac to the new network. Once you get access to the internet, restore your firewall to its original settings.

The last one worked for me. If you still have issues, go and look up support on Apple's website or various other forums dealing with the same issue. If these don't work, make a genius appointment and take it to the nearest Apple Store.