Unable to update iTunes: Related to Bonjour error "WSARecvMsg error 87"

I am running iTunes 9.2.0.61 on Windows 7 Ultimate x64. For some time, I have been unable to update iTunes to the latest version beyond what I have, regardless of what the latest version is.

Using Apple Software Update, I get the following error during the update:

"Errors occurred while installing the updates. If the problem persists, choose Tools > Download Only and try installing manually."

Accompanying this error in the Application log in Event Viewer are a few errors:

Event ID: Source: Occurrences:
100 Bonjour Service 7
11920 MsiInstaller 1

Event ID 100 from Bonjour Service has the following message:

-------

Log Name: Application
Source: Bonjour Service
Date: 10/31/2010 8:51:05 AM
Event ID: 100
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: WILL7
Description:
The description for Event ID 100 from source Bonjour Service cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer.

If the event originated on another computer, the display information had to be saved with the event.

The following information was included with the event:

WSARecvMsg failed (87)


The specified resource type cannot be found in the image file

Log Name: Application
Source: Bonjour Service
Date: 10/31/2010 8:51:05 AM
Event ID: 100
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: WILL7
Description:
The description for Event ID 100 from source Bonjour Service cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer.

If the event originated on another computer, the display information had to be saved with the event.

The following information was included with the event:

WSARecvMsg failed (87)


The specified resource type cannot be found in the image file

Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Bonjour Service" />
<EventID Qualifiers="0">100</EventID>
<Level>2</Level>
<Task>0</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2010-10-31T12:51:05.000000000Z" />
<EventRecordID>16990</EventRecordID>
<Channel>Application</Channel>
<Computer>WILL7</Computer>
<Security />
</System>
<EventData>
<Data>WSARecvMsg failed (87)
</Data>
</EventData>
</Event>

-------

Here is the error for event 11920 from MsiInstaller:

-------

Log Name: Application
Source: MsiInstaller
Date: 10/31/2010 8:51:06 AM
Event ID: 11920
Task Category: None
Level: Error
Keywords: Classic
User: WILL7\swsander
Computer: WILL7
Description:
Product: Bonjour -- Error 1920. Service 'Bonjour Service' (Bonjour Service) failed to start. Verify that you have sufficient privileges to start system services.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="MsiInstaller" />
<EventID Qualifiers="0">11920</EventID>
<Level>2</Level>
<Task>0</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2010-10-31T12:51:06.000000000Z" />
<EventRecordID>16991</EventRecordID>
<Channel>Application</Channel>
<Computer>WILL7</Computer>
<Security UserID="S-1-5-21-2626302321-2836749625-3976135476-1001" />
</System>
<EventData>
<Data>Product: Bonjour -- Error 1920. Service 'Bonjour Service' (Bonjour Service) failed to start. Verify that you have sufficient privileges to start system services.</Data>
<Data>(NULL)</Data>
<Data>(NULL)</Data>
<Data>(NULL)</Data>
<Data>(NULL)</Data>
<Data>(NULL)</Data>
<Data>
</Data>
<Binary>7B34314246304445342D354241452D344238382D414644332D383641333042323232313 8367D</Binary>
</EventData>
</Event>

-------

I checked my Services console and Bonjour was started. I can also stop and start it without issue. I searched for these errors, but most of what I found was trouble getting the Bonjour service to start and as you can see, this is not my issue.

I have also tried to update iTunes with Bonjour stopped and disabled and with my Eset NOD32 Antivirus software disabled, but neither of these steps made any difference. I do not have a third-party firewall on my PC, but I am using Windows firewall. I have also tried disabling the Windows firewall, but this made no difference.

Any help would be appreciated.