problem in preview mode- help!

[SB]

Hi,
I don't have the right terminology, but here goes.  OS X, rev 2.1.2

I make a new stack, save it, quit Rev.

Then I double-click the new stack to open it in the preview mode, 
without opening the main Rev program.

It opens, but here is the problem-- another stack opens with it.

The surprise stack is usually a splash screen stack from another 
stack-- this happens now with most stacks I open this way.  I have 
looked in the application browser and a bunch of other places, but 
can't see how these different stacks got  associated.

What have I done?  How do I get it to stop?

Thanks,

Sandy