Hi :^)
Seems to be the old Hard Drive Reset problem ;
When powering on your Amiga, does it take long or short time before the new hard disk begin to boot?
If the A4K waits for the HD finish it's spin up before booting on it and loose the HD upon reboot you can try to disconnect the IDE HD reset pin from the drive's cable (that's the red wire connected to motherboard IDE connector pin 1 and HD pin 1).
That worked for many many drives in the past :^)
Amigalement,
JF
