heres a latest manifestation of crashes on i386 with recent (july srcs).
nfs running between two i386 on the same kernel: 3c509 and WD8013 cards,
nfs running with -r/-w 4096 (would lock up w/o a -r/-w limit).  

Jul 11 17:34:36 atrium /netbsd: Data modified on freelist: word 0 of object 0xf8
6cc980 size 128 previous type free (0x0 != 0xdeadbeef)
Jul 11 17:34:36 atrium /netbsd: Data modified on freelist: word 0 of object 0xf8
6cc200 size 128 previous type free (0x0 != 0xdeadbeef)
Jul 11 17:34:36 atrium /netbsd: Data modified on freelist: word 0 of object 0xf8
6cc214 size 128 previous type ??? (0xa040210 != 0xdeadbeef)
Jul 11 17:34:36 atrium /netbsd: nfsd send error 47