I've been fighting this same thing . . . on my server. The account name and passwords (I tried TWO different accounts) are correct and DO work on other computers. Resetting the password had no effect. Same thing no matter which browser I tried. Pandora would connect and play as long as I didn't try to sign on.
Tried Disabling the anti-virus, the anti-malware, disabled the firewall, disabled all apps, transferred the Windows Firewall with Advanced Security Policy from another computer on which it WOULD work, and even changed the search engine (I'm not using VPN). NADA.
Then I remembered a while back that Pandora had given me some connection problems, and would ONLY work with my wireless connection active, and with ONLY my wireless connection active (activating the wired NIC would cause it to crash after a variable delay). I checked my wireless connections configuration . . . I found that under the Internet Protocol Version 4 (TCP/IPv4) settings, instead of allowing it to obtain an IP address (and DNS Server) automatically, there was a pre-configured IP address and the gateway address was missing. (I WONDER how that happened??? PIBKAC?).
ANYWAY, I reset the TCP/IPv4 IP configuration to auto, and disabled the wired NIC. It's working again. Now, If I can only figure out why the hard-wired connection fails . . . .
