Tomcat/admin; Exception retrieving attribute 'driverClassN..

Hi,

On my old machine the combination of apache_2_0_44-win32-x86-no_ssl.msi,
tomcat-4_1_18.exe and mod_jk-2.0.43.dll worked without problems.
(Jakarta is using j2sdk as provided bij NetBeansIDE-release351-win32.exe
=j2sdk1.4.2).
With the /admin application I could create contexts and datasources
(connect to Oracle-database, using classes12.jar) without problems.

I have installed the same software on a newer Compaq. The following
happened:
- http://cen1303w.domain:8088 => Tomcat home page (Since our proxy uses
8080, I had to switch to 8088)
- http://CEN1303w.domain/admin => Tomcat administration
- http://CEN1303w.domain/admin ->create context ->save => save succeeded!
- restart Tomcat
- http://CEN1303w.domain/admin => Internal server error
- http://CEN1303w.domain:8088 => Tomcat home page
- http://CEN1303w.domain:8088/admin -> Tomcat administration -> select
context -> datasources => Exception retrieving attribute 'driverClassName'

The only (slightly) relevant information I could find on internet dated
from 11 Sep 2003 (http://www.mail_archive.com/tomcat_user) but since I
had not created any previous datasources, it didn't really help me.

Who can give me a clue?

Ben