I have seen optical drives start to fail by not reading certain disks. It could also just be a conflict with this particular disk (maybe a problem with the copy protection, or something).
You could try checking with the optical drive manufacturer to see if there is updated firmware for it (or with the system manufacturer if the computer is an HP / Dell etc). That may help if the failure to read the DVD is a compatibility problem.
I have had my computer crash trying to access a damaged DVD. Maybe the generic drivers used in Safe Mode had a problem with the disk, but could not handle it properly...
