WebSphere trouble

[Jurgen]

Hi,

I'm having a very strange problem with WebSphere 6. We have a
WebSphere server, with 2 applications defined. Each application
contains a war-file. Each of these war-files has a JPA EntityManager
using a Hibernate implementation. The persistence unit is configured
the exact same way for both applications, they even have the same
name. We have set the websphere classloader to 'application first'.

Now when we access either one of these webapps, everything works fine.
When we access one of them and then the other, we get a
ClassCastException, saying 'org.hibernate.dialect.MySQLDialect is not
compatible with org.hibernate.dialect.Dialect'. I've checked the
classpath and there is only one version of Hibernate (3.2.6) available
throughout the server. Does anyone have any idea what could cause this
problem, or even better, how to solve it?

Jurgen