Oke Daniele,
YOu have got now the same problem i had before i figured out how to fix it.
Follow these steps and it works for sure.
1 ) Create a small partition with os3.1 e.g. 100mb.
2 ) Prep and format it, also make sure it is bootable.
3 ) Install os3.1 on that partition.
4 ) Now you can install IDEFIX on os3.1
5 ) After reboot you should be able to use the CDROM.
6 ) Use os3.9 Install and create a STARTUP DISK.
7 ) WHEN ASKED "copy your IDEFIX drivers with them"
8 ) Boot with disk and format the 100mb partition.
8 ) Install os3.9 but NOTE !! DON'T let it copy IDEFIX or you get trouble.
9 ) After the installation of os3.9 DO NOT REBOOT.
10 ) Click on the install os3.9 YES AGAIN. And click INSTALL CDROM drivers.
11) REBOOT.
12) Again make a STARTUP DISK and "COPY THE CDROM DRIVERS" to it. (the menu will do it for you)
13) With this startup disk you have the new file system, cdrom file system from os 3.9 instead of IDEFIX, there is also hd-toolbox on it.
14) If you boot with it you can prep the harddisk like any other drive and use it's full capacity.
15) Then install os3.9 and you're there.
Hope this will work and if you have any probs you can mail me at hvelthoven@hotmail.com or add me to messenger.
Greetz Henk
