i was experiencing that same problem on my laptop with windows xp home edition so i doubt it has anything to do with vista. what i think it was with mine was the IP kept getting jacked up if i left my computer on for a few days and i would have to restart it all the time but i never could figure out what was causing it, it was realy anoying. i personaly think IE is a sucky program anyways but that is just my opinion. but what i did was i switched to firefox and it stopped imediatly. and i think firefox is the best browser out there anyways now that ive used it. so you should probably try that. you can download firefox at
Mozilla - Home of the Firefox web browser and Thunderbird email client if you don't want to switch to firefox then maybe try updating your IE if you hav'nt already.