Just to clarify kiwig...
Your phone was originally running stock Samsung, Gingerbread, firmware and you rooted it with the CF-Root kernel, KI3, which was successful?
You then flashed stock Samsung, ICS, firmware for Hong Kong, OZS, to your phone... which includes a stock Samsung, unrooted, kernel.
You then tried to re-root your phone using the old Gingerbread firmware CF-Root kernel, again, which is not suitable for ICS?
You must now flash the complete OZS, ICS, firmware to your phone again and then re-root your phone, using the Dummies Guide, and use the correct ICS, CF-Root kernel, not the old Gingerbread one, this time.