Vista goes to page cannot be displayed with other traffic on netwo

Windows Vista Home Premium
1G memory

If vista is the only computer on the network it loads one page at a time ok.
Ifn there is any other traqffic acessing the internet on the network or if
more thyan one page is being loaded the pages come up page cannot be
displayed. This happens with all browsers. Also yahoo messanger will
disconnect under the same circumstances. When one page is being loaded there
are times when the page does not load all pictures or the page loads
incorrectly without html formatting and a lot of white space. I have a
windows xp machine and a xbox 360 on then network. Acess is throught the xp
machine now. The problem is still there if access is throught the vista
machine. The other machines have no problems.

It is as if the dns times out reall early.