ITunes wont upgrade my iPhone 4 iOS software.

Question

Hi. I recently updated my itunes to ver 10.2.1
I am now using a 16GB iPhone 4 but i used to have an iPhone 3GS.
I didnt have any problems with my 3GS but for some reason I can't download the iOS 4.3 software using my iTunes for my iPhone 4.
I tried using other iPhone's with my PC but it seems that the iTunes in my PC is the problem because the other phones can download the iOS 4.3 using other computers.
I tried reinstalling iTunes but that didn't solve the problem.
So what I did to upgrade my phone's iOS is I downloaded the iOS from a website and then i held the SHIFT key before clicking update in iTunes.
Now my iPhone is running iOS 4.3 but I would feel a lot better if someone can tell me how I can get my iTunes to download the iOS directly from Apple.
I did the network connectivity diagnostics test and this the result:
Microsoft Windows Vista Home Basic Edition Service Pack 2 (Build 6002)
Dell Inc. Inspiron 1318
iTunes 10.2.1.1
QuickTime 7.6.9
FairPlay 1.11.16
Apple Application Support 1.5
iPod Updater Library 10.0d2
CD Driver 2.2.0.1
CD Driver DLL 2.1.1.1
Apple Mobile Device 3.4.0.25
Apple Mobile Device Driver 1.55.0.0
Bonjour 2.0.4.0 (214.3)
Gracenote SDK 1.8.2.457
Gracenote MusicID 1.8.2.89
Gracenote Submit 1.8.2.123
Gracenote DSP 1.8.2.34
iTunes Serial Number 001AABD8031DE710
Current user is not an administrator.
The current local date and time is 2011-03-25 09:21:34.
iTunes is not running in safe mode.
WebKit accelerated compositing is enabled.
HDCP is not supported.
Core Media is supported.
Video Display Information
Intel Corporation, Mobile Intel(R) 965 Express Chipset Family
Intel Corporation, Mobile Intel(R) 965 Express Chipset Family
** External Plug-ins Information **
No external plug-ins installed.
iPodService 10.2.1.1 is currently running.
iTunesHelper 10.2.1.1 is currently running.
Apple Mobile Device service 3.3.0.0 is currently running.
** Network Connectivity Tests **
Network Adapter Information
Adapter Name: {1C7CE0E9-6C03-487F-8195-7EB997D1152F}
Description: Intel(R) PRO/Wireless 3945ABG Network Connection
IP Address: 0.0.0.0
Subnet Mask: 0.0.0.0
Default Gateway: 0.0.0.0
DHCP Enabled: Yes
DHCP Server:
Lease Obtained: Thu Jan 01 08:00:00 1970
Lease Expires: Thu Jan 01 08:00:00 1970
DNS Servers:
Adapter Name: {B23564F5-2E4D-428B-9770-198DE4043347}
Description: Broadcom NetLink (TM) Fast Ethernet
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: Fri Mar 25 08:38:07 2011
Lease Expires: Fri Apr 01 08:38:07 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 off.
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 unsuccessful.
The network connection timed out.
Connection attempt to Gracenote server was successful.
Last successful iTunes Store access was 2011-03-25 09:15:18
Can someone tell me what I can do? It seems that the main error here is that the connection to the firmware update server was unsuccessful. How can I fix this?

Answer 1

Either you missed some antivirus/antispyware software you have forgotten, you have some other software monitoring disk/internet usage, or your ISP is interfering with your net usage.