You may have to flush the DNS cache on your vista machine

Quote Originally Posted by tech-recipe.com
1. Click the Microsoft Vista Start logo in the bottom left corner of the screen
2. Click All Programs
3. Click Accessories
4. RIGHT-click on Command Prompt
5. Select Run As Administrator
6. In the command window type the following and then hit enter: ipconfig /flushdns
7. You will see the following confirmation:

Windows IP Configuration
Successfully flushed the DNS Resolver Cache.