Yes, thank you.

My first guess would be your ISP. Is your colleague's Mac on the same network you are on? Is there a router involved?

To eliminate XP, you could try a Linux Live CD like Puppy Linux. Create the CD f4rom the .iso file then boot the CD. If you can then connect to www.opendns.com and get a good page then it's something in your XP setup. If not then it's external to your computer, either your ISP, or router.

My colleague is on the same network, connecting to the internet through the same cable modem (we have a cable modem connected to a series of wireless access points).

It's wierd... Having connected mine via cat 5 as well (I was on wireless before) plugged directly into the cable modem, I still have the same problem. All the mac and linux computers on the network can access it fine, none of the windows ones can!

It's wierd.

I'll test from a live linux boot either later today or tomorrow.

This post has been edited by Remy Lebeau: Oct 21 2009, 07:06 PM

I tested booting into puppy linux (which btw is a fantastic little distro), and it loaded fine... Definitely something in my XP configuration...

After some re-testing, it turns out that I can talk to www-files.opendns.com (by loading www.opendns.com successfully) on all the MAC and Linux computers on the network, but none of the windows ones...

Not sure what to test next... ideas?

This post has been edited by Remy Lebeau: Oct 21 2009, 07:05 PM

Try these commands from a Command Prompt:

Flush DNS cache: ipconfig /flushdns
Reset WINSOCK entries to installation defaults: netsh winsock reset catalog
Reset TCP/IP stack to installation defaults: netsh int ip reset reset.log
Clear ARP Cache: netsh interface ip delete arpcach

If that doesn't fix the problem, try WinsockFix