Index: res/res_musiconhold.c
===================================================================
--- res/res_musiconhold.c	(revision 232854)
+++ res/res_musiconhold.c	(working copy)
@@ -50,6 +50,8 @@
 #include <dahdi/user.h>
 #endif
 
+#define REF_DEBUG
+
 #include "asterisk/lock.h"
 #include "asterisk/file.h"
 #include "asterisk/channel.h"
@@ -195,7 +197,32 @@
 static int reload(void);
 
 #define mohclass_ref(class,string)   (ao2_t_ref((class), +1, (string)), class)
+
+#ifndef REF_DEBUG
 #define mohclass_unref(class,string) (ao2_t_ref((class), -1, (string)), (struct mohclass *) NULL)
+#else
+#define mohclass_unref(class,string) _mohclass_unref(class, string, __FILE__,__LINE__,__PRETTY_FUNCTION__)
+static struct mohclass *_mohclass_unref(struct mohclass *class, const char *tag, const char *file, int line, const char *funcname)
+{
+	struct mohclass *dup;
+	if ((dup = ao2_find(mohclasses, class, OBJ_POINTER)) || (dup = ao2_find(deleted_classes, class, OBJ_POINTER))) {
+		if (_ao2_ref_debug(dup, -1, (char *) tag, (char *) file, line, funcname) == 1) {
+			FILE *ref = fopen("/tmp/refs", "a");
+			if (ref) {
+				fprintf(ref, "%p =1   %s:%d:%s (%s) BAD ATTEMPT!\n", class, file, line, funcname, tag);
+				fclose(ref);
+			}
+			ast_log(LOG_WARNING, "Attempt to unref mohclass %p (%s) when only 1 ref remained, and class is still in a container! (at %s:%d (%s))\n",
+				class, class->name, file, line, funcname);
+		} else {
+			ao2_ref(class, -1);
+		}
+	} else {
+		ao2_t_ref(class, -1, (char *) tag);
+	}
+	return NULL;
+}
+#endif
 
 static void moh_files_release(struct ast_channel *chan, void *data)
 {
@@ -1146,19 +1173,25 @@
 	
 	if (!strcasecmp(moh->mode, "files")) {
 		if (init_files_class(moh)) {
-			moh = mohclass_unref(moh, "unreffing potential new moh class (init_files_class failed)");
+			if (unref) {
+				moh = mohclass_unref(moh, "unreffing potential new moh class (init_files_class failed)");
+			}
 			return -1;
 		}
 	} else if (!strcasecmp(moh->mode, "mp3") || !strcasecmp(moh->mode, "mp3nb") || 
 			!strcasecmp(moh->mode, "quietmp3") || !strcasecmp(moh->mode, "quietmp3nb") || 
 			!strcasecmp(moh->mode, "httpmp3") || !strcasecmp(moh->mode, "custom")) {
 		if (init_app_class(moh)) {
-			moh = mohclass_unref(moh, "unreffing potential new moh class (init_app_class_failed)");
+			if (unref) {
+				moh = mohclass_unref(moh, "unreffing potential new moh class (init_app_class_failed)");
+			}
 			return -1;
 		}
 	} else {
 		ast_log(LOG_WARNING, "Don't know how to do a mode '%s' music on hold\n", moh->mode);
-		moh = mohclass_unref(moh, "unreffing potential new moh class (unknown mode)");
+		if (unref) {
+			moh = mohclass_unref(moh, "unreffing potential new moh class (unknown mode)");
+		}
 		return -1;
 	}