diff --git a/open-transcode.py b/open-transcode.py
index 173f344..f54e59d 100644
--- a/open-transcode.py
+++ b/open-transcode.py
@@ -3454,6 +3454,24 @@ class OpenCodecMaster(QMainWindow):
                 line_edit.setText(path)
 
     def _log(self, msg: str):
+        # Guard against signals (combo currentIndexChanged, knob valueChanged,
+        # etc.) firing during __init__ before self.log_box has been
+        # constructed. Without this, the first addItem() on any combo
+        # triggers its slot, which calls _log(), which dereferences
+        # self.log_box while it is still None -> AttributeError -> crashes
+        # the app on launch. Also buffer messages so they aren't lost.
+        if not hasattr(self, "log_box") or self.log_box is None:
+            buffered = getattr(self, "_log_buffer", None)
+            if buffered is None:
+                buffered = self._log_buffer = []
+            buffered.append(msg)
+            return
+        # Flush any messages that arrived before log_box existed.
+        buffered = getattr(self, "_log_buffer", None)
+        if buffered:
+            for m in buffered:
+                self.log_box.append(f"> {m}")
+            self._log_buffer = []
         self.log_box.append(f"> {msg}")
         sb = self.log_box.verticalScrollBar()
         sb.setValue(sb.maximum())