This is one of those very rare instances where CF provides absolutely no help in determining where the error resides. There is no stack trace in this error. No template of line number. As with all development-related error messages, it means next to nothing.
Multiple Google searches spew a myriad of tech talk and don’t come to any resolve. Again, I cannot tell you what part of my code is at fault here, since CF is not gracious enough to tell me. If someone has come across this error message before and found a resolve, I’ll try anything.
I’ve waste a good couple hours troubleshooting this, it’s time to ask for help rather than waste days more guessing what is in fault.
Have you got any XML stuff going on?
The times I’ve seen that error it’s been because of that and yeah it wasn’t too helpful for me either at the time. From what I recall though it was to do with whitespacing.
I was going to suggest that Ben Nadel has a few blog entries on it but looking just now I can see your name in the recent comments so I guess that’s not much help 
Hope you get it fixed 
Cheers,
James
The only XML things I have are the XML DTD. It is output in the onRequestStart function immediately after I reset the buffer.
<!--- Reset the buffer. --->
<cfcontent reset="true" />
<!--- Output XML Declaration. --->
<cfoutput><?xml version="1.0" encoding="utf-8" ?></cfoutput>
This is hopefully to ensure no whitespace appears before it, which I know can cause issues. All page processing previous to this point is wrapped in <cfsilent> tags.
Ben’s a good guy, and a solid developer; but his articles in those instances spoke well over my level of understanding. 