Typically this means either your disc is either damaged or your cdrom drive cannot read the disc properly because of an incompatibility with the burnt media.
I would first examine the disc to make sure there are no scratches or damage.
Otherwise you try the disc in another computer to see if the disc is read correctly, this would confirm that it is your drive that has problems reading the disc. The next step if this was the case would be trying to update the firmware for your disc drive because manufactures usually fix incompatibilities with disc media in each release.
Please follow the instructions carefully because incorrectly flashing the firmware of a disc drive may cause the drive to be permanently damaged.
Link to Update T400 disc drive firmware:
http://www-307.ibm.com/pc/support/si...cid=MIGR-70448