Hi
Check the article for Verbose logging : http://helpx.adobe.com/coldfusion/kb/enable-verbose-logging-coldfusion -10.html
NOTE : Enable Verbose strictly during maintenance.
Delete the isapi_redirect.log. Enable the verbose log ( level=debug) and then hit any of the non -existing .cfm page in your application and then you will get custom 404 error (may be not, may be truncated, may be entire page). Then change the level = info.
Provide the verbose log
Thanks
VJ