The first and most important rule of sharing a disk with MS-DOS and 
NetBSD is this:  both OSs must agree on the geometry of the disk.  For 
the sake of simplicity, I use the native geometry on the disk (which is 
reported by NetBSD at boot).

The second rule is to make sure that you don't ask DOS to cross the
1024-cylinder barrier.  If you have to (and I did on one of my disks), you
should put the DOS partition on the disk *before* installing NetBSD to 
avoid this problem.  (The disk, coincidentally, is the same WD disk 
you're having problems with.)

Hope this helps,

--scott