Help with internet connections - Alert message

Hi guys,

I have a very frustrating problem.
My macbook (2008) has always had perfectly working internet but last night an alert message came up where my airport icon is looking like this -
http://i.imgur.com/UkB5doG.png
and my internet completely stopped working.

I have been round all the forums with the advice like to delete my airport and then add a new one, add new locations or delete files from my system configuration and keychains.

I've managed to get it to connect a few times by manually entering the IP address but rather than connecting to the internet, the airport bars are full but still has no internet access.

I keep going around in circles and either losing the IP address and having to re enter it (which does nothing anyway) or have that horrid little icon pop up there my airport icon is.

My airport in network is green and saying connected but I just get a "You are no connected to the internet" page come up on all my internet browsers.

My housemate's macbook pro and my iphone are both connected to the wireless, so it's my mac that's the problem rather than the wifi.

Please help, it's driving me crazy!

IF it's connected but no internet connection - the problem is more than likely at the router - not on your machine.

Have you verified you in fact have internet connection at the router - typically provided by your ISP and/or reset the router?

I have, sorry I just added it as an edit.

I've reset everything numerous times and both my housemate's computer and my phone are connected without any issues at all.

I've also tried to plug the ethernet cable directly into my mac (I don't know if this is moronic, I'm just trying anything at this point) but when I do that it says it's still connected to the wifi rather than acknowledging the cable.

What's the IP address assigned to your machine - if it's 169., then you're not connected to the router.

Have you deleted the network you're attempting to connect with and then tried joining it - this time "manually" putting in the password again - not using the password stored in the keychain.

When the icon pops up and resets itself as it were, the self-assigned IP is a 169.
I go in and try and reset the IP manually with the IP address on my housemates mac which is a 192.
Should I be using something different?

I have deleted the wifi name and re added with the manual password and it does connect (in that the icon in network turns green) but I still don't have the internet come up on browsers.

Give this a shot:

click on the Airport icon - Join Other Network - then select your same network and put the password in again.

When I do, it goes back to the self assigned IP and the yellow icon in network, which then starts the circle again of typing in my new IP, which connects it and turns green and yet there's still no internet.

It's very annoying, I really appreciate your help.

There are so many things - aside from the basics I haven't mentioned - which I'm guessing you're already tried - may need someone better with troubleshooting network issues than I am. Can usually resolve my own, but not so good when I'm not sitting at the computer with this issue.

Next step on my own network, would be to blow away the wifi network at the router and set up a new one - shut down all devices and boot them up one at a time.


edit:
May want to go ahead and post what version of OS X you're using also.