Which OS have you got? Due to if you have WIN2k3, sometimes it doesnÂ´t work. Check if you have inside the Enviroment Variables (control panel-system-system properties-advanced-enviroment variables), JAVA_HOME=C:\JDK1.3.1._03
If you have installed the SDK after installing tomcat, then please reinstall tomcat.
Are you trying to run it as a service? does it work if you just start it from the start menu? if not, then try to start it from the command line by opening a command prompt cd'ing to "C:\Program Files\Hewlett-Packard\OpenView\service desk 4.5\service pages\bin" and executing "startup.bat". Post us the error messages if there are any. Also, post the log files and a screenshot so we can help yuo.