ok try typing again as root ::
hdparm -c1 /dev/hdX
to set the IO to 32bit...if it says permission denied, you can add it to a startup script (ex.. /etc/rc.d/rc.local or /etc/rc.d/rc.sysinit) and restart to make the changes take affect....and remember you only have to do this if it says permission denied when you try to change it...
and then try your dvd player and see if the same happens..
the same for X stands true as before in this statement also
and while your at it, check all your IDE devices connected to your machine with the same command hdparm -c -d and see if they are all set to 32bit and dma ON