Cannot connect to the iTune Store from within iTunes.

Question

Can not connect to the iTunes Store from within the iTunes program on my PC. Using iTunes 10.4 on a XP Sp3 system. Everything worked fine until a few days ago. Now the iTunes Store (Store) will not open. Tried rollback, disabling firewall, anti-virus etc. Not working. iTUnes Diagnostic says I can connect to the net but the screen remains blank, except "No connection to firmware update server" is listed in the Diagnostic.

Answer 1

Yes, I am running AVG Anti-Virus Free and was using Comodo Firewall. Uninstalled everything, iTunes Store still would not appear. Now using AVG and Windows Firewall, still can not get Store to come up. Diagnostic follows:
Microsoft Windows XP Professional Service Pack 3 (Build 2600)
GATEWAY 831GM
iTunes 10.4.0.80
QuickTime 7.7
FairPlay 1.12.20
Apple Application Support 2.0.1
iPod Updater Library 10.0d2
CD Driver 2.2.0.1
CD Driver DLL 2.1.1.1
Apple Mobile Device 3.4.1.2
Apple Mobile Device Driver 1.57.0.0
Bonjour 3.0.0.2 (333.2)
Gracenote SDK 1.9.1.485
Gracenote MusicID 1.9.1.102
Gracenote Submit 1.9.1.133
Gracenote DSP 1.9.1.43
iTunes Serial Number 0012ABA010AA0F38
Current user is an administrator.
The current local date and time is 2011-08-16 18:21:15.
iTunes is not running in safe mode.
WebKit accelerated compositing is enabled.
HDCP is not supported.
Core Media is supported.
Video Display Information
ATI Radeon HD 3400 Series
**** External Plug-ins Information ****
No external plug-ins installed.
iPodService 10.4.0.80 is currently running.
iTunesHelper is currently not running.
Apple Mobile Device service 3.3.0.0 is currently running.
**** Network Connectivity Tests ****
Network Adapter Information
Adapter Name:          {11221FB9-2BC2-4E8D-A170-06A6BEBCCB07}
Description:          Intel(R) PRO/100 VE Network Connection - Packet Scheduler Miniport
IP Address:          192.168.0.103
Subnet Mask:          255.255.255.0
Default Gateway:          192.168.0.1
DHCP Enabled:          Yes
DHCP Server:          192.168.0.1
Lease Obtained:          Tue Aug 16 17:24:27 2011
Lease Expires:          Tue Aug 23 17:24:27 2011
DNS Servers:          192.168.0.1
Active Connection:          LAN Connection
Connected:          Yes
Online:                    Yes
Using Modem:          No
Using LAN:          Yes
Using Proxy:          No
SSL 3.0 Support:          Enabled
TLS 1.0 Support:          Enabled
Firewall Information
Windows Firewall is on.
iTunes is enabled in Windows Firewall.
Connection attempt to Apple web site was successful.
Connection attempt to browsing iTunes Store was successful.
Connection attempt to purchasing from iTunes Store was successful.
Connection attempt to iPhone activation server was successful.
Connection attempt to firmware update server was successful.
Connection attempt to Gracenote server was successful.
Last successful iTunes Store access was 2011-08-16 18:19:43.
Ran another test today an hour or so ago, same result except "Connection attempt to firmware up......" failed.