Creating a Help System

I have written several XML files that I converted into an HTML Help System.
I completed this about a month ago, and all was well. I have now made some
updates to some of my files, and am trying to create a new HTML Help
system. I am using Xalan, and every time I try to transform my files, I get
the following error message:

<Location of error of unknown>XSLT Error
<javax.xml.transform.TransfromerException> :
java.net.MalformedURLException: no protocol: Title.xml


Thanks.

JB