Why do I a kernel panic if I connect my SCSI Iomega Zipdrive?

Question

I have start up problems in 10.4.11 (kernel panic), if my SCSI Iomega Zipdrive
is connected to its AC power transformer and the Adaptec SCSI expansion card in
my G4 PowerPC. I can no longer start the computer even after multiple restarts,
the restarts always end in a new kernel panic.
As soon as I unplug the transformer power supply from the Zipdrive, I no longer have kernel panics.
I used the Zipdrive together with Adaptec SCSI CARD 2906 which came with its own software that after installation shows up as Adaptec290X-2930.kext driver, version 1.1.0, in System/Library/Extensions.
This setup has worked for me from OS 10.2 through all later updates up to 10.4.5, but has not worked since.
In trying to solve the kernel panics I examined the extension files in the system profiler, and noticed that there are suddenly all sorts of additional
Adaptec extensions, namely
Adaptec39160.kext
Adaptec29160x.kext
Adaptec78XXSCSI.kext
What do they do?
On the other hand I found that the original Adaptec290X-2930.kext I installed with the card no longer had any dependencies and was apparently not supported by the system.
I also tried to install, after reading some similar posts, the latest version of the card driver, namely version 1.2.0, which I had down-loaded from Adaptec's site.
I still could not start up with the Zipdrive connected as all I would get is more Kernel Panics.
If I switch the Start Up System to OS 9.2, I have no problem with start-up or kernel panics, even when the Zipdrive is connected, and it works as it should.

Answer 1

The mystery of kernel panics when I connect my zip drive is getting more complex,so I have to add more info to my original post.
The original post had an error: I had downloaded Adaptec290X-2930.kext version 1.1.0 (not 1.2.0) from the Adaptec website, and installed it.
In the system profiler/extension I now get info that Adaptec290X-2930.kext dependencies are "satisfied", but its "integrity" is "unknown".
I also notice that the system profiler/extension (list) no longer lists any of the extensions named:
Adaptec39160.kext
Adaptec29160x.kext
Adaptec78XXSCSI.kext,
however in /system/library/extensions they are still there.
I also can now no longer see the zip drive on the desktop when I start in system 9.2.2, as a matter of fact I could do so only once.
I then went to delete OS 10.4.11 from one of the 4 drives on my computer, including its 9.2 system folder. After that I loaded system 10.2 from an old install disk I had onto that drive, together with its classic 9.2.
I then started that disk in 9.2, with the zipdrive connected - and it showed on the desktop. I was able to copy its floppy's content. I did the same with one more floppy loaded after.
OK I got it working, I thought. I now tried restarting the computer in 10.2,
the zip drive showed on the desktop, but when I tried to change the floppy the 10.2 froze with a kernel panic. I could not get it restarted, more kernel panics only, until I finally pulled the power cord from the zipdrive, then it started without problem.
I switched the start-up back to 9.2, on the same disk.
I could start the computer with the zip connected, however as soon as I tried
load a new floppy (I tried several) it would now also freeze up with kernel panics. Since I still could start it with the Zip connected, I opened the SCSI Control Panel in 9.2 and found that the Zipdrive was connected at port 7 and the SCSI properly terminated. In more detail I found that the Zipdrive cannot be loaded because of a system error "-36" which I analysed as an "I/O error - not supported".
I then examined the startup items in the system profiler and found at
/System/Library/StartupItems/Disks the following:
Provides: Disks
Requires: SecurityServer
Uses: System Tuning
I now suspect that this SecurityServer was updated recently to somehow mark all disks loaded on the external SCSI as "suspect". It seems to extent its control from my three OS 10.4.11 loaded disks on my computer to now even cause kernel panics in the one reloaded with OS 10.2.
It probably takes advantage of the "user" files which identify all disks on this computer by my name.