Well, I'll be d*mned. Have no idea why I tried this, but it worked. I went into Mac preferences and changed the magic mouse button around so the left button becomes a right click and the right button becomes a left click...and boom, the stacks library is working like a champ.
I'm almost afraid to say that it's fixed. Thought it was last time. Keeping my fingers crossed.
Thanks for the suggestions...who would have 'thunk' it would work by changing the orientation of the mouse buttons.
I guess I'm a genius ;>) We'll see how long this temp 'fix' works. Now if I can only get used to clicking the right mouse button when I want left and vice versa, I'll be fine.
P.S. Wish I knew why this change is working...