Cannot start process designer

We have recently upgraded to LDMS 8.8 which includes (as I understand it) a cut down version of Process Manager.

I have follwed the steps to set up a sql database, and used the Database Utilty to enter all our details. All of the 'Test' buttons work fine within this utility.

When I try to run Workflow Designer (WorkflowManager.exe) , the Database Utility starts instead.

I can watch this in taskmanager - workflowmanager.exe runs for around 2 seconds, then closes and databasemanager.exe fires up.

Anyone any ideas ?

EDIT

The above happens on the core server. If I attempt to start Process Designer on a workstartion I get the error :

"A system error has occured. Internal error: Object reference not set to an instance of an object"