Ok, I have no idea if this will help you at all or not but I'm going to go ahead and share my findings on this.
What I found was if you have multiple URL's for a web server (for instance they can use www.help.com
but you only setup websphere to work with people coming in on www.help.com
you may encounter this error. With IIS (this is where I had the error, so all the other servers will need to look into how their setup is done) when you install the websphere plugin, it places the ISAPI filter in the root of the webserver. This means that anyone coming into that webserver will be parsed through the Websphere ISAPI filter. This is ok, if you configure Websphere in the vhosts.properties file to recognize all of your host headers (such as www.help.com www.helpme.com
if you only tell websphere about one on those host headers, then it will place an informational message in the web server log that is basically trying to say "I don't know what www.helpme.com
On our servers here at work, this damn near brought production down, due to the fact it wrote over 1.2 gigs worth of logs to our log directory in less than a week (yes it's a very large site).
Anywya, hope this helps, and hope I explained it somewhat clearly.