libdvdread reports invalid IFO files

i've got 2 dvds (Futurama Volume 3, Discs 1 and 3) which libdvdread says have 
invalid IFO files.  One title on each disc won't play.  In both cases in the 
function ifoRead_VTS() the vtsi_mat structure is getting filled with garbage 
so there's some problem reading the disc.  However, when I mount the discs 
and manually check the IFO file, I can see that its valid, and the discs work 
in standalone DVD players.

I'm guessing the discs have some errors (although they're brand new) which the 
system UDF driver recovers from but libdvdread doesn't.  how can i fix this 
so the disk gets read correctly?
-- 
Keith Lyon <[email protected]>