I have posted this patch to gnomebaker-devel list which probably wasn't a good idea... So once again: GnomeBaker allocates GtkSelectionData structures using g_new0() and then calls gtk_selection_data_free() ro release them. The latter function however expects a pointer to a memory allocated as a GLib memory slice. This leads to random crashes (I think also those reported here in the forums). Please consider applying the attached patch.