DVD-Rs burned on a Panasonic E20 or E30 set top DVD recorder still are unreadable in OS X.2.1.
These discs work in OS X.1.5, OS 9.2.1 (on the same drives as tested in OS X.2), as well as in Windows and on set top DVD players.
It looks like X.2.1 still has wonky CD/DVD support.