Symptom: Service doesn't start on Windows start up. prism is installed, but service always appears as "Stopped" under services in Task Manager or services.msc.
Cause: On boot up there is a mad rush for all of the services with StartUp type "Automatic" to start. They do so all at the same time. If the prism service doesn't start up in the time that it has requested (2 minutes I think) then it won't start. This is hypothesised to have happened on a till with a huge load of AVG services running.
Solution: First and foremost, ensure you have the latest version installed. If it's still failing, change the StartUp type to "Automatic (Delayed)", this way it only starts up the prism Service after all of the "essential" services in the Automatic category have started. This option is only available in Windows Vista and above.