[whpalmer4]

It's funny, OmniPlan 1 worked the way you want, and it seemed like everyone complained that it didn't work like it does now :-)

What OmniPlan 2 does when you enter a new task well after the project has started is to put a start constraint on it for today's date. That's what you want to change, not the start date, because it is that constraint which is controlling when the action starts (and the calendar for the project and any assigned resource(s)). Just click the little black circle with an x in it right below the start date field in the inspector. You can select multiple actions at once and do it for all of them in one shot.

Be sure to send in the crash reports along with any details on what you are doing. I've found it to be reasonably stable over the time it has been a released product; looks like about one crash a month. Might be worth downloading a fresh copy into a newly created account and see if the crashes persist there. I would also contact the support ninjas with Help->Send Feedback and ask them to investigate your crash reports.