zen 7sp1 bootcd (also 7, 6.5, etc.)

On Dell latitude D420 and D620 laptops we have a problem when we try to
manually partition the harddrive.
img pc1 ntfs 20000 (this one works fine - always)
img pc2 ntfs (this one doesn't work)

The problem is that the img dump geo reports a number of cylinders twice as
much as there are on the harddrive (ide ICH7, toshiba hdd, /dev/hda, not
sata). So when we want to fully extend the sized of the second drive we
get an incorrect size for the second partition. How can we fix this. The
linux kernel and fdisk finds the correct size of the harddrive, but not img
utility.
Thanks for any help.