I am messing with the XML Web Part and I am having issues with it
retrieving the xml file off a web server on another computer. If I
copy and paste the xml contents into the XML Editor and copy and paste
the XSL stylesheet into the XSL Editor the content comes up fine.

As soon as I try to link to the XML file it gives me the error:

Cannot retrieve the URL specified in the XML Link property. For more
assistance, contact your site administrator.

I cannot figure out why it is doing this. If I choose Test Link the
data comes up just fine.

If I copy and paste the XML data in and link to the XSL Stylesheet I
get the error of:

The XSL specified by the XSL property or XSL Link property is not
valid, or the XSL file cannot be accessed. Make sure you have
specified a valid XSL style sheet for this Web Part, or if the XSL
file is linked that it can be accessed by the server. For assistance,
contact your site administrator. More about making XSL files accessible