Web app crashes in IDEA, when loading PoolMan, running Tomcat 404 or 406

Apologies in advance. This didn't seem to be a great place for posting this help request, but I don't know of another place for it. Please let me know of a better place to post the question, if you know of one.

I've been having problems running a web app within IDEA. I set up the project according to the instructions provided by Tom Maxwell at the Phasesoft site. The application does run under IDEA w. Tomcat... sometimes. Whether it runs or crashes at startup seems to depend in part on which Tomcat version I choose as target in IDEA. The problem almost certainly has to do with the interaction of Tomcat, the PoolMan code base that the app uses to handle database connection pooling, and my configuration of this web app project within IDEA. The evidence that it may be a configuration issue in IDEA is indicated below.

If I run the application from within IntelliJ IDEA, the app runs properly without crashing as long as I have IDEA point to the Tomcat version that is built into Sun's Sun One Studio 4 that I also have on my machine, namely, Tomcat 4.0.1. But when I run the app within IDEA, and have IDEA point to the version of Tomcat that's built into NetBeans3.4, version 4.0.4, the app crashes when it tries to create and configure the connection pool manager (PoolMan). You might ask: "why doesn't he try running against the latest 4.0 version of Tomcat itself...?" Well, I have tried. When I run the app within IDEA and have IDEA point to the current 4.0.x version of tomcat, version 4.0.6, it crashes, and at the same point: when attempting to create and configure the PoolMan connection pool manager.

BUT: I can run the app outside of IDEA, against version 4.0.6 of tomcat running on its own and no crash occurs when the app is creating and configuring the connection pool manager. This is why it seems the problem might have to do with IDEA or my configuration of it.

What could be going on???

Any help would be greatly appreciated.