If you've defined a sitewide error handler in the settings page of ColdFusion administrator, you might find yourself running into the following bug: When an error occurs in a template, ColdFusion MX will generate the output of the template up to the point of the error, then it will display the sitewide error template. This can cause the page to display improperly.
Fortunately, Macromedia has provided a workaround in the TechNote below:
ColdFusion MX: Incorrect Output Behavior When Using Sitewide Error Handler