I had a user ask why they could not access a Salelogix opportunity when they clicked the hyperlink from the Account Opportunity Tab.
It would flash to the Detail View and then go blank.
In the user Options , there is a setting for the Opportunity Default Lookup Group.
Make sure there is no (conditions) criteria that is limiting the records for this Default Lookup layout.
Change the group to a very simple group with no conditions.
You should not be able to access your new Opportunity.