First , check your code to ensure you're not accidentally triggering a
CFABORT tag or
abort() function somewhere which would cause CF to stop processing.
If you're not aborting processing prior to output, this could be related to a problem with the Tomcat connector or its settings. First I'd try tuning the connector settings as outlined in this Adobe blog post:
Tuning ColdFusion 10 IIS Connector configuration
If the connector settings aren't tuned properly it can cause the connector to run out of threads and crash the IIS Application Pool.
Next, it could be a bug in the connector itself. Adobe has a newer build available for those who request it. There was a specific problem with the connector that was related to 404 handlers, but requesting the updated DLL file may help. See this Adobe bug for more information on the updated connector file and who to contact about getting it if needed.
ColdFusion 10 - Bug 3488063 - Note that the updated connector that fixes this bug is included in Updater 14, so if you apply that updater and reinstall the IIS connector it should correct the issue on this bug if this was the problem.