Upgrading = bad!!! Hehe...in general I wouldn't recommend upgrading from another operating system. Especially when doing such an "invasive" upgrade. I've had a similar problem but it only affected my internet access and I resolved it by putting in the dns addresses for my cable modem. It looks like you've exhausted any possible solutions to the problem...I hate to say it but I might try a fresh install of the OS. *maybe* removing the networking protocols from the network properties and then re-adding them after a reboot might help. You got me man...
