If this works on v6, it sounds like a bug we've already fixed, though I'm not sure which one.
Does the application itself start, or does the profiler just get stuck? One possibility is that the executable is starting up and then not getting any further, so check if it's running in task manager or not.
I know of a rare issue where if a profiled application gets detached from the profiler UI, future applications will take around 30 seconds to initialise (which gives the impression that they're not starting at all). Shutting down the originally profiled application will fix the problem.
Do you see a 'cannot CoCreate profiler' message in the system event log? If the application is starting but the profiler fails to initialse for some reason, this will happen.
Red Gate Software Ltd.