XLS Support / HCS Tools - Library conflict

Hi KNIME people,

we have observed a conflict between our extensions "HCSTools" and the "KNIME XLS support". Now I'd like to know if you can explain the following behaviour and if you have any idea how to avoid the problems. The following steps (done under MacOS Snow Leopard but the OS should not matter) should help you to reproduce the problem:

- Install KNIME 2.4.0

- Open KNIME and install extensions (in the given order):

KNIME XLS - Support

HCS Tools (http://idisk-srv1.mpi-cbg.de/knime/beta-channel/)

- Restart and import the attached workflow

-> The Join-Layout node throws an exception. (which is thrown by a constructor of the class XSSFWorkbook)

If the XLS Support is installed after the HCS Tools or if it's uninstalled and reinstalled again, the problem does not occur anymore. It's somehow a conflict of the library which is used to read Excel files. Both Plugins use the Apache POI but with different version (we use 3.7-beta, the XLS Support uses 3.6). May that be an explanation?