Vaio running vista fails to load page but connection is ok

hi

I have a newish vaio running vista and use IE8 and Firefox. The problme i have is pages failed to load in either browser occasionally but the connection is fine. If I diagose windows doesnt find any problems with the connection either and the only way to get pages loading again is to disconnect and then reconnect.

I alos have an old acer running xp which works fine all the time on the same netowkr. i have chnaged channels on the router tryign 1, 6, 11 and 13 and tried b and g but still get the same problem.

could it be a software issue on the vaio as all else seems fine? I am at my wits end with it as it renders the laptop virually unuseable and I cant think of anything else to try. all help appreciated.