I know a few people have had this problem but not seen an answer and why this is occuring.

When you are on vista (ultimate) casually doing anything random, after maybe an hour or a few days the DNS server error comes up. Ive tried repairing the connection but still nothing.

I am running off a linksys wireless router, on virginmedia cable modem. the other laptops connection still works when the other drops out so i know its not the router or modem problem.

The only way i am aware of (which is seriously inconvienient) is to reboot the PC. grrr

You can try clearing your DNS cache and see if that helps.....

Open a command prompt....from the Start menu, select Run > In the box/"open field", type cmd.exe

type or copy and paste ipconfig /flushdns press 'enter'