Steps to reproduce:
1. Pick a .shape file that doesn't currently have a textbox and try to add one
e.g. add line :
<textbox x1="0.5" y1="0.75" x2="7.5" y2="4.75"/>
with any numbers whatsoever
2. Start up DIA
3. Get this in a terminal window and dia dies

** (dia.exe:4092): WARNING **: No attribute text (00000000) or no data(00000000)
 in this attribute

(dia.exe:4092): GLib-GObject-CRITICAL **: file gobject.c: line 1561 (g_object_re
f): assertion `G_IS_OBJECT (object)' failed


Stack trace:
You show me how to do a stack trace in windows (blah) and I'll send you one

Other information:
Windows XP SP2 - all patches
Thanks :)