The problem is most likely that the system BIOS doesn't support hard drives larger than 8GB (or however big the drive is). To correct this issue:
- If your motherboard manufacturer has a BIOS update, install it. The update may have added support for the large hard drive.
- If there is no BIOS update available from your motherboard manufacturer then you can check with eSupport.com to see if an update is available that will work for you.
- Install an ATA-66/100/etc. controller and move your drives to it. The controller should have a BIOS which will support larger hard drives. If it doesn't support a very large hard drive, there may be firmware updates available at the manufacturer's website.
- The BIOS may need to have the drive controller in LBA mode for the full drive size to be seen. If LBA mode doesn't work and a Normal mode is available, try that.