DVD problem

I recently purchased an eMachine T3256 and I am having an unusual
problem with the DVD drive. It seems to function fine in every area
except one, which is copying data from the last gigabyte or so of every
DVD (all the files at the end of the catalog). When I try to copy from
the end of the catalog any DVD I get this message "data error - cyclic
redundancy check." I have tried copying data from the end of the
catalog from multiple DVD discs of different brands: the same thing
happens every time. Another thing: the DVD drive in my other computer,
a mac G4, has no trouble copying this data which the DVD drive in this
computer refuses to copy... Has anyone heard of a problem like this
before? COuld this be the sign of a defective drive, or could there be
another cause?
Another thing I don't understand. There are a number of discs I have
which this drive simply refuses to mount, CDs and DVDs. I can't even
get a catalog to come up for them. My Mac mounts all of these discs,
but I would think the PC should too, since they are all UDF or hybrid.
Anyone know what might be causing this? Does it sound like something
that might be related to the problem above, or would this be a separate
problem, caused by something else?
Thanks to all who reply.