after some digging I found this post, it may or may not fix your problem.
Quote:
On XP go to the Taskbar and right click the network connection icon and select Status.
Then once that is up, click on the properties button on the Status window.
In the scrollable list go down til you find Internet Protocol (TCP/IP) and click it and select properties.
On this page click the "Use the following DNS server addresses:" setting and set it to 4:2:2:1.
Hit Ok and then the close button to save the change.
Now I got this from an SE customer service rep(Amazing I know ^^) and it seems to work, I only tried this on my pc but it should work on xbox360(under network settings I think) as well.
Not sure if this will help everyone, but for the 0019 people it should, PLEASE NOTE: this is only a stop gap til Iowa Telecom(or your provider) fixes their DNS server. You should call them and find out when they get it fixed and then follow the above steps, except switch it back to find DNS automatically. I'll try and post when they do and any other steps needed to get running smoothly again.
If that doesn't work, give SE a call.