IIS appcmd on Windows Server 2003

You're probably hitting a MaxConnection issue. Take a look at chapter 10 of Improving .NET Application Performance and Scalability, specifically this section on Connections.

You might need to add a section in the machine.config like this:

<connectionManagement>
  <add address="*" maxconnection="12"/>
</connectionManagement> 

Which is detailed in the MSDN Library.

The best place to start is %windir%\system32\inetsrv\config\schema. The IIS_schema.xml file has the definition for everything in IIS (except for some extensions which are in other files in that folder).

The schema files shows the default, where it should be set in the config and sometimes the range.

The next place to check is the IIS reference guide. Here's the page that has the MinBytesPerSecond: http://www.iis.net/ConfigReference/system.applicationHost/webLimits

You can set these using appcmd or editing applicationHost.config directly. Make sure to take a backup before starting. appcmd add backup 'backup before starting minbytespersecond'