If you receive an error after the Disk Partitioning Setup phase of the installation saying something similar to:
"The partition table on device hda was unreadable. To create new partitions it must be initialized, causing the loss of ALL DATA on this drive."
you may not have a partition table on that drive or the partition table on the drive may not be recognizable by the partitioning software used in the installation program.
Users who have used programs such as EZ-BIOS have experienced similar problems, causing data to be lost (assuming the data was not backed up before the installation began).
No matter what type of installation you are performing, backups of the existing data on your systems should always be made.