Nick:
Thanks for the quick reply. Relating to the info you added, here's what I see:
1. DISPLAY is set to just ":0" (ie: without the quotes, and no ".0"). Changing it to ":0.0" -- the failures occur as before.
2. The logfiles you mention show the following:
======================================== .xdebug_tkmedit: ------------------ tkmedit started: Fri Jan 26 13:40:02 2007
tkmedit
$Id: tkmedit.c,v 1.274.2.3 2006/04/15 00:13:10 nicks Exp $ $Name: stable3 $
------------------ .xdebug_tksurfer: empty
========================================
So... nothing obvious seems to jump out here.
Graham