My wife's MacBook doesn't seem to connect to the Internet using domain names and I can't figure out what is going on. Here is what I've tried:

- Verifying my other MacBooks and iMac; they work just fine

- Restarting the computer

- Resetting my modem and router

- Pinging website IP addresses, domain names, the router, and other computers on the network come back a success with no packet loss

- Using Firefox or Safari and attempting to go to IP addresses produces the queried page, albeit somewhat slow

- Adding in different DNS servers does not work

- Flushed DNS and regular cache but with zero success

- Killed/restarted mDNSResponder (thru Terminal and Activity Monitor) and still nothing

Do you all have any other resources or suggestions? Just to let everyone know, she is running Leopard and is 100% up to date on software and updates. I am open to upgrading her to Snow Leopard but would like to avoid that for now (still getting settled after being married). Thanks for all of your help! I will post updates as I try different things...