segfault on return to gtk_main()

[brenden grace <grace flipt com>]

I currently have a callback fuction called
void
on_butApply_clicked                    (GtkButton       *button,
                                        gpointer         user_data)

it loads a string and then

gtk_entry_set_text(GTK_ENTRY(tmpEntryTo), addLine);

then returning to the calling function where it segfaults (i believe
the calling function is gtk_main -- i am a little new to gtk).

this happens usually with stings of length greater than about 80 chars
... but sometimes of shorter strings. is there soemthing i should know
about writing large strings to entry widgets or should i continue to
assume that i have a memory error/leak somewhere before this code
segment. (i am sure it is not dying during or before the above
gtk_entry_set_text)

thanks for your help.

-- 
brendengrace
flipt.com