Webmethod portal fails to load with xcercesImpl.jar

We have a third party API that make usage of the xcercesImpl.jar.
Once we copy the Jar to the lib folder under the portal, the portal server no longer loads, and spits out a long error message.
Have anoyone here solved or met this issue before.

----The error message
2007-09-24 14:12:10 EDT (Framework : WARN) - Error initializing component: startJetty

xercesImpl.jar is already in Portal’s classpath so you don’t have to add another version of it. Doing so you confuse Glue.jar classloader.

Please remove the jar you added.