We've been having problems with running out of session on the production server. To assist this I wanted to reduce the time-out limits from 20 minutes to 10...
Edit the file "D:\Program Files (x86)\SAP BusinessObjects\Tomcat6\webapps\BOE\WEB-INF\web.config", and look for the setting at the bottom of the file....
<session-config>
<session-timeout>10</session-timeout>
</session-config>
Restart tomcat service and that should be it.
