Xphoton crash with full TCP/IP stack

$ slay Xphoton
$ slay io-net
$ io-net -del900 -ptcpip -ppppmgr
$ ifconfig en0 192.168.1.16 up
$ route add default 192.168.1.1
$ Xphoton -once

When I start an X program at this point (I used Redhat source navigator,
which is a TCL/TK program – this was build from source), I can observe
garbled video in some windows (partial background etc).

Upon exiting Source Navigator, Xphoton crashes.
This doesn’t happen with the tiny tcpip (-pttcpip) stack.

Do I need something like a different library to be linked in ? Or is it
a plain ol’ bug ?

Hardware :
Compaq ProSignia
PIII 500, 128MB

/usr/sbin/pci

PCI version = 2.10

Class = Network (Ethernet)
Vendor ID = 10b7h, 3Com Corporation
Device ID = 9055h, 3C905B Fast Etherlink XL 10/100
PCI index = 0h
IO Address = 1000h enabled
Mem Address = 48000000h enabled
Expansion ROM = ffee0000h disabled
PCI Int Pin = INT A
Interrupt line = 11

Class = Multimedia (Audio)
Vendor ID = 1274h, Ensoniq
Device ID = 1371h, ES1371 AudioPCI
PCI index = 0h
IO Address = 1080h enabled
PCI Int Pin = INT A
Interrupt line = 11

Class = Mass Storage (IDE)
Vendor ID = 8086h, Intel Corporation
Device ID = 7111h, 82371AB PIIX4 IDE Controller
PCI index = 0h
IO Address = 10e0h enabled
PCI Int Pin = NC
Interrupt line = 0

Class = Display (VGA)
Vendor ID = 10deh, Nvidia Corporation
Device ID = 28h, Riva TNT2 Riva TNT2
PCI index = 0h
Mem Address = 40000000h enabled
Mem Address = 42000000h enabled
PCI Int Pin = INT A
Interrupt line = 11

uname -a

QNX test 6.00 2000/09/13-14:09:41edt x86pc x86