My uptime was really starting to look good until yesterday.
Fortunately I keep a reboot.log

Apr  2 19:56:50 zen /netbsd: NetBSD 1.2D (ZEN) #11: Wed Apr  2 09:50:52 EST 1997
Apr  5 03:35:40 zen /netbsd: NetBSD 1.2D (ZEN) #11: Wed Apr  2 09:50:52 EST 1997
Apr  5 03:35:44 zen savecore: reboot after panic: vm_object_paging_begin
Apr  5 18:53:41 zen /netbsd: NetBSD 1.2D (ZEN) #12: Sat Apr  5 18:39:29 EST 1997
Apr  7 07:41:46 zen /netbsd: NetBSD 1.2D (ZEN) #12: Sat Apr  5 18:39:29 EST 1997
Apr 26 09:57:16 zen /netbsd: NetBSD 1.2D (ZEN) #12: Sat Apr  5 18:39:29 EST 1997
May 11 01:50:49 zen /netbsd: NetBSD 1.2D (ZEN) #12: Sat Apr  5 18:39:29 EST 1997
May 11 01:50:53 zen savecore: reboot after panic: vm_object_paging_begin
May 11 16:11:13 zen /netbsd: NetBSD 1.2D (ZEN) #12: Sat Apr  5 18:39:29 EST 1997

Those are all panics - but most don't procude a dump as the reset
button is the only thing that works.  Most are vm related, though the
one of April 26 is due to the console keyboard being wedged [my kids
seem to manage to wedge the console (pc3) _every_ time they use the
computer - I normally use an old sun386 as an xterm.]

I did get a dump from the last panic: vm_object_paging_begin, though the
dump tells me zip.

# gdb -k /sys/arch/i386/compile/ZEN/netbsd.gdb /var/crash/netbsd.10.core
GDB is free software and you are welcome to distribute copies of it
 under certain conditions; type "show copying" to see the conditions.
There is absolutely no warranty for GDB; type "show warranty" for details.
GDB 4.11 (i386-netbsd), Copyright 1993 Free Software Foundation, Inc... 
panic: vm_object_paging_begin
#0  0x300000 in ?? ()
(kgdb) bt
#0  0x300000 in ?? ()
(kgdb) q

Is no-one else having problems with semi-regular panics?

--sjg