I'm currently stumped on why I can't connect to the internet on my Macbook Pro...

I first noticed the problem today when I tried to connect to an ad hoc network I made on an older macbook. Everytime I try to go onto the network through wifi it drops me immediately. So I tried connecting the ethernet wire straight into my laptop and on the system preferences it says self-assigned IP.

Now on the older macbook (the one that is working properly) the connection the addresses are acquired automatically using DHCP but it just refuses to work on my newer macbook.

I've tried everything I can think of already from going over the settings to resetting preferences to even reinstalling my mac OS X and it's still not working properly. Earlier today though, my newer macbook crashed so I was thinking some settings got corrupter but shouldn't have the reinstall fixed that...

Any help would be appreciated as I really need to get back to work The mac with problems is my 2.8Ghz 15" macbook pro, the recent model.