One possible cause is that the WinPE boot is unable to access the hard disk on your target system for some reason. I don't know the age of your machines or the make, but assuming that the hardware is from the last year or two, the hard disk is very likely to be SATA.
Although WinPE 2 has basic SATA support, there are many new chipsets out there that require you to add Vista 32 bit drivers to the WinPE boot disk for the SATA chipset, so that the hard disk can be mounted by WinPE.
As a test measure, you could go into the BIOS settings and check if you can set the hard disk to "compatibility mode" which will cause the hard disk to appear to be an older parallel ATA (IDE) device, which will not require a specific driver for WinPE to see it.
If this is not the issue, then it would surely be a simple test to nuke the hard disk partitions with GDISK or GPARTED from a USB stick (again assuming that your boot system can actually mount the hard disk) and then try deploying the image again.
If you want to experiment with WinPE outside the Ghost framework and create some WinPE boot media of your own design, then check out the following article: Adventures with WinPE Symantec Connect
If a standard WinPE boot device created this way cannot read your system's hard disk then neither will the Ghost configured WinPE, as they are the same basic code.