Ubuntu Ibex to Jaunty, now can't launch terminal

[david-8uUts6sDVDvs2Lz0fTdYFQ at public.gmane.org]

Hi.  I just updated my work laptop from Intrepid to Jaunty (i686) using
Update Manager.  Most things seem to work fine (pulseaudio failed to
allocate shared memory pool, etc), but my big problem is when I launch
Gnome terminal, I get a dialog box saying  "There was an error creating
the child process for this terminal".  This is true for the default
profile, or SSHing to another box.

I tried to use Synaptic to install konsole, and it said "Error failed to
fork pty".

Any clues?