Strange Win32Status=64 errors in IIS 6 logs on new webserv..

While investigating the IIS 6 logs on our new Windows Server 2003
webserver running 2 web apps, I noticed that around 10% of the hits on
the webserver have a Win32 Status of 64 and most of those requests
return zero bytes to the browser. Interestingly these requests
typically have HTTP statuses of 200 which indicates everything was OK.

Here are the characteristics of these strange HTTP requests in the IIS
logs...
- Win32 status = 64
- Zero bytes returned to the client/browser
- HTTP status = 200 (OK)
- Time taken on the server seems typical for the type of file
- Occurs on various file types (ASPX, ASP, GIF, JS, JPG, etc.)
- Occurs on Impact Enterprise and another web app on the same server
- Occurs when webserver is hit by LAN and WAN users
- Occurs on our production and non-production servers in datacenter A
- Occured on previous IIS5 server in datacenter A (see paragraph below)
- Does not occur on IIS5 server in datacenter B

We are looking into the Event Tracing for Windows (ETW) logs available
in Windows Server 2003 SP1, but they don't seem to help isolate the
problem. In IIS 5 we saw some zero byte responses, but they had HTTP
status of 400 which is "bad request". There are a limited number of
Google matches on this problem and no solutions. Microsoft looked at
our Netmon log and correlated it with the IIS logs. In all 4 Win32
errors we correlated, there was a TCP reset sent to the IIS server
which may have caused the issue. We looked at 500k hits on an IIS 5
webserver at another data center (B) in the company and they had zero
Win32Status=64 errors. On the datacenter A server in question, we had
250k errors in 2.5M hits. This leads me to think it might be a network
issue for datacenter A.

I'm concerned that if these pages are returning zero bytes they may be
affecting the functionality of the applications especially if they are
in supporting files like .JS or rscripts.asp. Even if they are not
causing functionality problems, they are causing performance
degradation.

Anyone else seen Win32 status of 64 in their IIS logs?

FYI. Here's a LogParser query to check for them...
"C:\Program Files\Log Parser 2.2\LogParser.exe" "SELECT
TO_LocalTime(TO_TIMESTAMP(date, time)) as LocalDateTime, *,
WIN32_ERROR_DESCRIPTION(sc-Win32-Status) as Win32StatusDesc INTO
ImpactWin32_64.csv FROM logs\*.log WHERE LocalDateTime >
TO_TIMESTAMP('01/1/2006 00:00','MM/dd/yyyy hh:mm') AND
sc-Win32-Status=64" -i:IISW3C -o:CSV

Thanks for your help.