isaacsy:
1) you can send an email to
omniplan@omnigroup.com directly if you can't launch OmniPlan. Just describe your problem and mention which build you're running (probably beta 6). In this specific case, including a sample report (as described above) would be very helpful.
2) Try deleting your OmniPlan preferences file before launching. If you have OmniPlan preferences set to re-open files you had open last time, it could be getting stuck trying to open one of those files.
3) The only reason I mention the network connection is because OmniPlan (like all our apps) does check your local network for other copies of OmniPlan running to make sure you're obeying the licensing. It also checks in with our server (if you have auto-check for update enabled) to make sure you're running the latest build. Both of these actions occur fairly early in the launch process, so if your network access is in a funny state, it might be confusing OmniPlan.