After spending hour in "computer Hell" over the past few days, I have at least discovered the apparent source of the problem: every one of my Windows 7 systems, after the application of Windows 7 SP1 via Microsoft Update, looses its ability to connect to our Verizon FIOS router properly via a wired Ethernet connection (i.e. directly or through a switch). Instead of properly recognizing the existing workgroup network, Windows 7 insists it is on a public network and fails to establish an Internet connection. The only way I've been able to get this (my primary desktop dev system) connected reliably to the internet has been to install a USB wireless adapter on it. That works just fine. But the wired Ethernet connection from this (and all my other wired connection systems) went south after SP1 and none of the numerous things I've tried to fix it has worked. Nice job screwing things up, Microsoft. Anyone got any idea how to resolve this problem? Thanks. All the best, will Willaim F. Zachmann, Canopus Research Inc.William F. Zachmann

Try deleting your Ethernet connection and recreating it. Go to Network and Sharing Center. Click on Change adapter settings. Right click on Local area Connection and select delete. Go back to Network and sharing center and click on set up a new connection and follow the prompts. Jerry

Furthermore, you can try to update NIC driver, also update BIOS to the latest version. And temporally disable firewall and IPV6 for test. Regards, Leo Huang Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.