no internet connection currently available try again

Hi,
While my network icon in the system tray remains constant with the little globe indicating an internet connection, my Internet aware applications keep throwing up the "No Internet connection currently available" error message. When I click Try again, it usually works just fine.
It happens all the time... whether I am right in the middle of downloading messages, accessing WebPages or what have you. I have noticed it while surfing in explorer, syncing my MSN mail accounts in Outlook, posting and retrieving Usenet messages in Windows Mail.... pretty much all net applications.
Windows Media Player is more abstinent than the rest. When clicking on a media file online, WMP opens but then gives the error "Windows Media Player cannot play the file. if the file is located on the Internet, connect to the Internet..." Sometimes it works when I retry... mostly not. If I right click on the item, it will download just fine then I can play it but that's a hassle.
Any ideas? I am using an nVidia nForce network controller with the provided Vista driver and connected via Ethernet. Ironically, when I use "Report an Issue" in beta client, it doesn't prompt me to "try again" when it can't see an internet connection so it never connects successfully.
Thanks,
Dave