--- blender-2.43/source/blender/yafray/intern/export_File.cpp.zthreads	2006-12-21 14:47:27.000000000 +0100
+++ blender-2.43/source/blender/yafray/intern/export_File.cpp	2007-03-12 22:53:18.000000000 +0100
@@ -2014,6 +2014,11 @@
 bool yafrayFileRender_t::executeYafray(const string &xmlpath)
 {
 	ostr.str("");
+
+	/* Can't have 0 threads */
+	if (re->r.YF_numprocs < 1)
+		re->r.YF_numprocs = 1;
+
 	if (re->r.mode & R_BORDER) {
 		ostr << command_path << "yafray -c " << re->r.YF_numprocs
 		     << " -r " << (2.f*re->r.border.xmin - 1.f)
--- blender-2.43/source/blender/yafray/intern/export_Plugin.cpp.zthreads	2007-03-12 22:42:18.000000000 +0100
+++ blender-2.43/source/blender/yafray/intern/export_Plugin.cpp	2007-03-12 22:54:08.000000000 +0100
@@ -253,6 +253,11 @@
 	params["bias"] = yafray::parameter_t(re->r.YF_raybias);
 	params["clamp_rgb"] = yafray::parameter_t((re->r.YF_clamprgb==0) ? "on" : "off");
 	// lynx request
+	
+	/* Sometimes YF_numprocs = 0 */
+	if (re->r.YF_numprocs < 1)
+		re->r.YF_numprocs = 1;
+		
 	params["threads"] = yafray::parameter_t((int)re->r.YF_numprocs);
 	blenderYafrayOutput_t output(re);
 	yafrayGate->render(params, output);
--- blender-2.43/source/blender/src/buttons_scene.c.maxthreads	2007-04-17 16:24:59.000000000 +0200
+++ blender-2.43/source/blender/src/buttons_scene.c	2007-04-17 16:44:41.000000000 +0200
@@ -1929,6 +1929,7 @@
 		if (G.scene->r.YF_gamma==0.0) G.scene->r.YF_gamma=1.0;
 		if (G.scene->r.YF_raybias==0.0) G.scene->r.YF_raybias=0.001;
 		if (G.scene->r.YF_raydepth==0) G.scene->r.YF_raydepth=5;
+		if (G.scene->r.YF_numprocs<0) G.scene->r.YF_numprocs=1;
 		if (G.scene->r.YF_AApixelsize==0.0) G.scene->r.YF_AApixelsize=1.5;
 		if (G.scene->r.YF_AAthreshold==0.0) G.scene->r.YF_AAthreshold=0.05;
 		if (G.scene->r.GIpower==0.0) G.scene->r.GIpower=1.0;