2nd desktop not receiving packets

I am using a linksys WRT54GS router to enable wireless internet. my second desktop computer is not receiving packets, and thus cannot access the internet. I've done ping tests, I cannot ping the 'bad' computer from my 'good' computer, and the 'bad' computer is only able to ping itself. The 2nd desktop (the 'bad' one) is able to connect to the router and my wireless network, but only has a "limited or no connection". There is also a lack of Defualt Gateway on the 'bad' computer as well as everything else (dns servers, etc). When i try to repair the connection, windows tells me it cannot complete the renewal of the ip adress.

any help is much appreciated.

Mine did this and I turned of Windows Firewall and it worked fine. Just a guess though.

I've done that already, but it didn't do a thing to help. This just randomly seemed to happen, it's been working fine for around a month now. A virus scan turned up nothing, so i'm stuck.