Strange behaviour of ErrorDocument 500

Hi all.

I have an IBM HTTPServer 2.0.47 attacking a WebSphere.

Server version: IBM_HTTP_Server/2.0.47.1-PK29827 Apache/2.0.47

I've configured ErrorDocument 500 in a virtualhost. Here's the
virtualhost configuration:

Listen cndir.lig.local:92
<VirtualHost cndir.lig.local:92>
ServerName cndir.lig.local
RewriteEngine on
RewriteRule ^/$ /Test [R,L]

ErrorDocument 500 /Test/error/errormantenimiento.htm

ErrorDocument 400 /Test/error/error404.jsp
ErrorDocument 404 /Test/error/error404.jsp
DocumentRoot /opt/IBMIHS/htdocs/integracion_vhost/
ErrorLog /opt/IBMIHS/logs/integracion_vhost/error.log
CustomLog /opt/IBMIHS/logs/integracion_vhost/access.log combined
<Directory /opt/IBMIHS/htdocs/integracion_vhost>
Options -Indexes FollowSymLinks MultiViews
AllowOverride All
<IfModule mod_acess.c>
Order allow,deny
Allow from all
#Deny from all
</IfModule>
</Directory>
</VirtualHost>


My problem is, if I shut down the WebSphere server, I get an error 500
message in error.log, and the error page configured in the
ErrorDocument rule, but if I just force an error 500 to appear by
mistyping an URL, what I get is a 500 entry in the access.log, and the
code returned by the server.

10.194.100.240 - - [18/Dec/2006:15:25:45 +0100] "GET
/OficinaVirtual/capturaRiesgoAutos.do?reqCode=capturaDato&deleteSe ssion=true
HTTP/1.1" 500 81 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT
5.1; SV1; .NET CLR 1.1.4322)"

It's as if the won't recognize an error 500 returned by the server as
an error. It thinks it's just a normal answer, and so does not apply
the ErrorDocument directive to it.

Any ideas about what's happening here?

So, no one has advice for me?