--- blender2.42/source/blender/yafray/intern/export_Plugin.cpp.ncpus	2006-07-23 12:10:55.000000000 +0200
+++ blender2.42/source/blender/yafray/intern/export_Plugin.cpp	2006-07-23 12:47:37.000000000 +0200
@@ -189,6 +189,10 @@
 			cerr << "Error loading yafray plugin: " << PIL_dynlib_get_error_as_string(handle) << endl;
 			return false;
 		}
+		
+		/* sometimes YF_numprocs = 0... */
+		if (re->r.YF_numprocs < 1)
+			re->r.YF_numprocs = 1;
 		yafrayGate = constructor(re->r.YF_numprocs, YafrayPluginPath());
 		
 		cout << "YafRay plugin loaded" << endl;