only 512k on the MMR.. makes no difference if its installed, removed, setup, or not setup... it still crashes... so its not the 512k on the MMR that's the issue, it's probably the MMR not working properly with the A590 scsi controller...
the MMR won't work in 68000 fall back mode at all with the A590, to boot from the HDD, with the 68000, I had to completely remove the MMR.