I just built a kernel with DUMMY_NOPS turned off, and it cured the
unpredictable behavior on my Compaq Aero.  Now it predictably fails in the
same way every time.  It gets as far as populating wd0, and I can mount the
disk and look at the files.  But fsck fails miserably, with torrents of
error messages, and copy_kernel fails (I forget how).  This is the 1.1
kernel.