Seems to happen with specific configurations. Here I can use HD and CDROM as a slave without problems. My default configuration:
80GB MorphOS HD: ide.device / 0 (master in channel 1)
HP CDRW: ide.device / 3 (slave in channel 2)
I have 2 AmigaOS HDs (from my ex-A1200) which I can attach to any free IDE slot (channel 1 slave or channel 2 master).
(Btw when installing HD from Amiga make sure you have boot priorities right or you may get wrong OS there.)
