Hi there, LadyM.
I'm jumping in to let you know that the Error 3371 when opening QuickBooks is already a reported issue. Our engineers are already investigating to check what's causing the issue.
We will email you as soon as the issue is resolved. If you haven't yet, please call us so we can add you to the notification list. Follow the steps provided in the previous replies to get our contact details.
Thanks for visiting us again.