I have a Micron P90 machine with an Adaptec 2940 SCSI controller. The boot process hangs after it detects no SCSI devices during the boot sequence. I tried the new boot image from the updates page, with the same bahavior. The Errata suggest copying the aix7xx module after the mouse configuration screen appears, but I don't get that far into the boot sequence.
Fixed in 6.0 release.