Their return policy is pretty generous (6 months), and IMO exchanging a defective disc after three years is kinda unusual.
Rosetta Stone will exchange a product that you purchased directly from Rosetta Stone via
www.rosettastone.com, telephone or a Rosetta Stone kiosk within six months (i.e., 180 days) of your purchase.
I think it could be that Rosetta Stone has problems with the latest Leopard OS as there are several people with the same problem, if you do a google search.
I think this looks likely to work, last post at the bottom:
http://www.mac-forums.com/forums/os-...tta-stone.html