Error parsing xml when name of source file does not end with ".xml"

Error parsing xml when name of source file does not end with ".xml"

            There seems to be a problem when reading XML from a file whose name does not end in ".xml".  THis only occurs when the jQuery is run from a web server; it does not happen when run locally.

I will attach a .zip file with the source code I'm using as well as two versions of a very simple xml file to use - one version has a ".xml" appended to its name, the other has a ".dat" extension.  Both contain exactly the same data.

You can also find the file on my server here:
http://www.mit.edu/~rjc/jQuery/loadXmlTest/loadXmlTest.html

Load the file into your browser, and enter the following in the two fields:
myXml.xml
book
(Click the load button)

It will find 3 book elements in the myXml.xml file.

Now enter myXml.dat and press the load button. It will fail with some nonsese error (at least I can't determine what it means).

Again, running this locally does not exhibit this behavior; the XML is always parsed correctly, no matter the name of the file which contains it.