I have reviewed that URL previously.
Our web.config has:
<httpRuntime executionTimeout="45" maxRequestLength="2000000"/>
And I don't have an applicationHost.config in the machine.
We are running Windows Server 2003 R2.
The file being uploaded is less than 100K, so the issue is not likely the size of the file.
The test URL I provided works with about any size file in MSIE, but Firefox and Chrome do not.