> ifconfig media 10baseT, the link ok light on the hub goes out
> immediately. The only way to get the interface into a working state is
> to reboot the box entirely. AFAICT this only affects my ne2000, the
> 3c509 I also have in the same box seems to work fine even after ifconfig

Exact same thing happened to me, I have a 3c509b plugged into my broadband
modem and a PCI NE2000 to my LAN. Removing the 'media 10baseT' part from
/etc/ifconfig.ne0 fixed the problem. Output from dmesg follows:

NetBSD 1.4W (SUN) #1: Sun Mar 26 19:27:33 PST 2000
    root@ip010160021130:/usr/src/sys/arch/i386/compile/SUN
cpu0: family 6 model 0 step 0
cpu0: Cyrix 6x86MX (686-class)
total memory = 65088 KB
avail memory = 58912 KB
using 839 buffers containing 3356 KB of memory
BIOS32 rev. 0 found at 0xfb190
PCI BIOS rev. 2.1 found at 0xfb1c0
pcibios: config mechanism [1][x], special cycles [1][x], last bus 1
PCI IRQ Routing Table rev. 1.0 found at 0xfdc80, size 112 bytes (5 entries)
PCI Interrupt Router at 000:07:0 (VIA Technologies VT82C586 (Apollo VP) PCI-ISA Bridge)
PCI Exclusive IRQs: 11 12
mainbus0 (root)
pnpbios0 at mainbus0: nodes 11, max len 106
pci0 at mainbus0 bus 0: configuration mode 1
pci0: i/o space, memory space enabled
pchb0 at pci0 dev 0 function 0
pchb0: VIA Technologies VT82C597 (Apollo VP3) Host-PCI Bridge (rev. 0x04)
ppb0 at pci0 dev 1 function 0: VIA Technologies VT82C598 (Apollo MVP3) PCI-AGP (rev. 0x00)
pci1 at ppb0 bus 1
pci1: i/o space, memory space enabled
vga0 at pci1 dev 0 function 0: Nvidia Corporation product 0x002c (rev. 0x15)
wsdisplay0 at vga0: console (80x25, vt100 emulation)
pcib0 at pci0 dev 7 function 0
pcib0: VIA Technologies VT82C586 (Apollo VP) PCI-ISA Bridge (rev. 0x47)
pciide0 at pci0 dev 7 function 1: VIA Technologies VT82C586A IDE Controller
pciide0: bus-master DMA support present
pciide0: primary channel configured to compatibility mode
atapibus0 at pciide0 channel 0
cd0 at atapibus0 drive 1: <10X, , 1.3E> type 5 cdrom removable
cd0: 32-bit data port
wd0 at pciide0 channel 0 drive 0: <FUJITSU M1623TAU>
wd0: drive supports 16-sector pio transfers, lba addressing
wd0: 1623 MB, 3298 cyl, 16 head, 63 sec, 512 bytes/sect x 3324996 sectors
wd0: 32-bit data port
wd0: drive supports PIO mode 4, DMA mode 2
pciide0: primary channel interrupting at irq 14
wd0(pciide0:0:0): using PIO mode 4, DMA mode 2 (using DMA data transfers)
cd0(pciide0:0:1): using PIO mode 3
pciide0: secondary channel configured to compatibility mode
wd1 at pciide0 channel 1 drive 0: <QUANTUM FIREBALL1280A>
wd1: drive supports 8-sector pio transfers, lba addressing
wd1: 1222 MB, 2484 cyl, 16 head, 63 sec, 512 bytes/sect x 2503872 sectors
wd1: 32-bit data port
wd1: drive supports PIO mode 4, DMA mode 2
wd2 at pciide0 channel 1 drive 1: <IBM-DALA-3540>
wd2: drive supports 16-sector pio transfers, lba addressing
wd2: 516 MB, 1049 cyl, 16 head, 63 sec, 512 bytes/sect x 1057392 sectors
wd2: 32-bit data port
wd2: drive supports PIO mode 3, DMA mode 1
pciide0: secondary channel interrupting at irq 15
wd1(pciide0:1:0): using PIO mode 4, DMA mode 2 (using DMA data transfers)
wd2(pciide0:1:1): using PIO mode 3, DMA mode 1 (using DMA data transfers)
pchb1 at pci0 dev 7 function 3
pchb1: VIA Technologies VT82C586 (Apollo VP) Power Management Controller (rev. 0x10)
ne0 at pci0 dev 14 function 0: RealTek 8029 Ethernet
ne0: 10base2, 10baseT, 10baseT-FDX, auto, default [0x00 0x30] auto
ne0: Ethernet address 00:00:b4:a0:7f:7e
ne0: interrupting at irq 12
isa0 at pcib0
ep0 at isa0 port 0x300-0x30f irq 10: 3Com 3C509 Ethernet
ep0: address 00:20:af:70:1a:7c, 8KB byte-wide FIFO, 5:3 Rx:Tx split
ep0: 10baseT, 10base5 (default 10baseT)
com0 at isa0 port 0x3f8-0x3ff irq 4: ns8250 or ns16450, no fifo
com1 at isa0 port 0x2f8-0x2ff irq 3: ns8250 or ns16450, no fifo
pckbc0 at isa0 port 0x60-0x64
pckbd0 at pckbc0 (kbd slot)
pckbc0: using irq 1 for kbd slot
wskbd0 at pckbd0: console keyboard, using wsdisplay0
lpt0 at isa0 port 0x378-0x37b irq 7
pcppi0 at isa0 port 0x61
midi0 at pcppi0: PC speaker
spkr0 at pcppi0
sysbeep0 at pcppi0
isapnp0 at isa0 port 0x279: ISA Plug 'n Play device support
npx0 at isa0 port 0xf0-0xff: using exception 16
fdc0 at isa0 port 0x3f0-0x3f7 irq 6 drq 2
isapnp0: read port 0x203
wss0 at isapnp0 port 0x534/4,0x388/4,0x220/16 irq 5 drq 1,0
wss0: Crystal Codec WSS/SB: CS4236B compatible
audio0 at wss0: full duplex, mmap
opl0 at wss0: model OPL3
midi1 at opl0: WSS Yamaha OPL3
joy0 at isapnp0 port 0x200/8
joy0: Crystal Codec GAME
joy0: joystick not connected
isapnp0: <Crystal Codec, CSC0010, , CTRL> port 0x120/8 not configured
isapnp0: <Crystal Codec, CSC0003, , MPU> port 0x330/2 irq 9 not configured
biomask eb45 netmask ff45 ttymask ffc7
wd2: no disk label
boot device: wd0
root on wd0a dumps on wd0b
root file system type: ffs
IP Filter: v3.3.8 initialized.  Default = pass all, Logging = enabled
wsdisplay0: screen 1 added (80x25, vt100 emulation)
wsdisplay0: screen 2 added (80x25, vt100 emulation)
wsdisplay0: screen 3 added (80x25, vt100 emulation)
wsdisplay0: screen 4 added (80x25, vt100 emulation)
wsdisplay0: screen 5 added (80x25, vt100 emulation)
wsdisplay0: screen 6 added (80x25, vt100 emulation)
wsdisplay0: screen 7 added (80x25, vt100 emulation)
wsmux1: connecting to wsdisplay0
wd2: no disk label