Problems installing NetBSD-acorn32 v2.0

Hi

I've got a SA RPC, with RISC OS 3.70 onto which I'm trying to install 2.0 of
NetBSD. I've previously installed and used NetBSD 1.5 and 1.6, so I'm not a
*total* newby at this.

I've partitioned the (60GB) hard drive I intend to use for NetBSD, with 512MB
allocated to RISC OS.

My problems start when I try to boot the installation kernel. After I double
click on the installation kernel (extracted from BtNetBSD.spk), the memory
information scrolls past, it spins the progress indicator indicating that it's
loading the kernel, gets as far as saying
'bye bye from RISC OS!'
and then freezes. I've left it a couple of minutes, and there really is nothing
happening. The only solution is to press the reset button.

I've tried increasing the wimpslot for !BtNetBSD to 8000k, but get the same behaviour. [It's a 64MB machine so there's no problem with allocating that much space]

Has anybody else experienced anything similar, or have any suggestions on what to try?

As a side issue, I've noticed a couple of things after rummaging inside 
ftp://ftp.netbsd.org/pub/NetBSD/NetBSD-2.0/acorn32/  
 - the netbsd-INSTALL.gz file in installation/kernel decompresses to a
   different size to the InstKern file in BtNetBSD.spk
   [I get the same behaviour with both decompressed kernels]

 - the installation/misc/MD5 file does not include a checksum for the 
   BtNetBSD.spk file in the same directory.

Thanks in advance for any suggestions.

Neil