Apache/Vhost failures

Hi there, I am having problem configuring virtual hosting between Apache 2.0.58
and Resin 3.0.19 (and .18).  My Apache2 is configured to use "named" vhosting
where 2 hostnames are mapped onto the same IP address - this works for sure and
I have tested it from both names outside of resin.  Each vhost has a separate
"webroot" for non-dynamic content, but share the same webapps directory so
the web-applications can be used on both sites.  The area of resin config that
controls this looks something like:

    <host id="site1" host-name="site1" root-directory=".">
      <web-app id="/" document-directory="/u/webserver/htdocs/site1"/>
    </host>

    <host id="site2" host-name="site2" root-directory=".">
      <web-app id="/" document-directory="/u/webserver/htdocs/site2"/>
    </host>

  </server>
</resin>

Funny thing is, I have had this working, but made a recent change to allow
site1 to be accessed via its IP address in our development environment, and
didn't restart Apache2.  Since Apache2 has now been restarted that fix no
longer works, but worse the original configuration now no longer works and only
site2 is accessible (when site1 is accessed apache2 serves the JSP source to
the browser).

Can anyone shed any light on this ?

Cheers,
Andy