When you are debugging a CFC and you throw an error, you sometimes get a dreaded "page cannot be displayed" message. The reason this pops up is that the "output" attribute of the component is set to "no". If you set the output to "yes" you will see the full error messages.
<cfcomponent output="yes" ....>
Remember, there are usually good reasons to set it to "no". When you have finished debugging it probably should
be set to "no" - unless you are using CFC's to display or send data back to the user. That's not the way I like to do it. Pages or custom tags are fine for display, CFCs are for data and logic - at least that's my take.