There's  yet another snapshot GENERIC kernel in 
    ftp://ftp.netbsd.org/pub/NetBSD/arch/pmax/netbsd.3100

This kernel has a fix for some interrupt-related bugs, which I
committed to -current earlier today.  This kernel also includes Michael
Hitch's probable but as-yet-uncommitted fix for the 3100 disk-hang.

Together, these changes should significantly improve stability on
3100s.  (We can't say for sure that the disk-hang problem is fixed
until everyone who's reported a hang says the problem is fixed, and/or
we get sii debugging logs that pinpoint the problem.)s

I'd encourage anyone who's reported problems with a 3100 -- either
related to disk-hangs on async-capable drives, or not -- to try this
kernel. 

(Michael Hitch has already distributed the sii patch in source form to
a few people; the snapshot kernel lets anyone who's had problems with
a 3100 try out the fix.  If you already have the sii source patch, you
should apply it to kernel source supped tomorrow to get the other changes.)