Well, I have had a couple of interruptions so it isn't the entire solution, but it did make a large difference. I'll let you know if I find anything else that works
Mine was a clean install. But, I may have found a fix for it. I changed my network adapter settings and locked it down to 100/full and my performance has increased significantly. It's been several hours and I haven't had any issues with web pages not opening.
I have a similar problem but I never see a failure of the network connection itself. MSN and Ventrilo continue to run, I just lose the http portion of my connection. It takes a minute or so for the internet to start working again.