This is more of an FYI for others, as I've just found the solution.

I am running Tomcat 5.5.28 and the Lightstreamer, (always want to call this lightsaber for some reason), separately.

I configured the Tomcat to run on port 9999, (as I have various other servers on the same machine). I have Lightstreamer running on port 9898. After following the "DEPLOYING THE DEMOS ON AN EXTERNAL WEB-SERVER" document, running the Tomcat server, and then running the Lightstreamer server, I was getting:

¬í�sr� eginMessageß,„‹Î6�L�profilest�Ljava/lang/String;L�versionq�~�xppt�1.0ysr�5javax.manageme nt.remote.message.HandshakeErrorMessageÇ�Ü^>rI� L�detailt�Ljava/lang/String;xpt� invalid stream header: 47455420y

This was in Firefox. IE had another way of dealing with the error.

Long story short: Tomcat can't use port 9999 as the Lightstreamer uses that port for the JMXMP Connector for JMX.

I changed the Tomcat port to run on 18080, 8080, and another one and it runs fine.

Took me about an hour to figure this guy out, so hopefully this lil' post will help others.