im sorry for the network install i ve never had the pleasure to commit it.
perhaps you have to specify the subfolder of the cd: /slackware/
like when you can plug another hard drive:
put all the FILES of the slack cd in subfolder of a fat32 partition ex.: c:/slackware
boot the cd
do the cfdisk job without touching at the fat32 partition ^^
---------note the id of the fat32 drive ex.: /dev/hda1 or /dev/hdd2 or......
run the setup normally
the setup will detect the fat32 and said the changes wont apply until reboot: no matter.
after that you have to choose the installation source. Choose hard disk partition
give the drive id
you have to specify the subfolder: /slackware
this folder u can see it when u make the step 1
read this bestseller: http://slackware.com/install/