diff --git a/app.py b/app.py
index 6df01bf..0c76c30 100644
--- a/app.py
+++ b/app.py
@@ -52,6 +52,7 @@ AVAILABLE_LANGUAGES = config["languages"]["available_languages"].split(",")
 ollama = OllamaHandler()
 OLLAMA_AVAILABLE = ollama.is_available()
 OLLAMA_MODELS = ollama.get_available_models() if OLLAMA_AVAILABLE else []
+DEFAULT_OLLAMA_MODEL = ollama.get_default_model() if OLLAMA_AVAILABLE else None
 
 
 def load_model(model_name: str) -> WhisperModel:
@@ -221,14 +222,23 @@ def create_interface():
                                 )
                                 ollama_model_dropdown = gr.Dropdown(
                                     choices=OLLAMA_MODELS,
-                                    value=OLLAMA_MODELS[0] if OLLAMA_MODELS else None,
+                                    value=DEFAULT_OLLAMA_MODEL,
                                     label="Ollama Model",
                                     visible=False,
                                 )
+
+                                def toggle_summary(checked):
+                                    if checked and not ollama.is_available():
+                                        gr.Warning(
+                                            "Ollama is not available. Please check your Ollama server."
+                                        )
+                                        return {"value": False, "visible": False}
+                                    return {"value": checked, "visible": checked}
+
                                 summarize_checkbox.change(
-                                    fn=lambda x: {"visible": x},
+                                    fn=toggle_summary,
                                     inputs=[summarize_checkbox],
-                                    outputs=[ollama_model_dropdown],
+                                    outputs=[summarize_checkbox, ollama_model_dropdown],
                                 )
                         transcribe_btn = gr.Button("Transcribe", variant="primary")
 
@@ -317,14 +327,26 @@ def create_interface():
                                 )
                                 yt_ollama_model_dropdown = gr.Dropdown(
                                     choices=OLLAMA_MODELS,
-                                    value=OLLAMA_MODELS[0] if OLLAMA_MODELS else None,
+                                    value=DEFAULT_OLLAMA_MODEL,
                                     label="Ollama Model",
                                     visible=False,
                                 )
+
+                                def toggle_yt_summary(checked):
+                                    if checked and not ollama.is_available():
+                                        gr.Warning(
+                                            "Ollama is not available. Please check your Ollama server."
+                                        )
+                                        return {"value": False, "visible": False}
+                                    return {"value": checked, "visible": checked}
+
                                 yt_summarize_checkbox.change(
-                                    fn=lambda x: {"visible": x},
+                                    fn=toggle_yt_summary,
                                     inputs=[yt_summarize_checkbox],
-                                    outputs=[yt_ollama_model_dropdown],
+                                    outputs=[
+                                        yt_summarize_checkbox,
+                                        yt_ollama_model_dropdown,
+                                    ],
                                 )
                         yt_process_btn = gr.Button("Process Video", variant="primary")
 
diff --git a/ollama_handler.py b/ollama_handler.py
index 82188cf..25cde98 100644
--- a/ollama_handler.py
+++ b/ollama_handler.py
@@ -69,21 +69,50 @@ class OllamaHandler:
             logger.error(f"Error fetching Ollama models: {str(e)}")
             return []
 
+    def validate_model(self, model_name: str) -> tuple[bool, Optional[str]]:
+        """Validate if a model exists and return the first available model if not."""
+        available_models = self.get_available_models()
+        if not available_models:
+            return False, None
+
+        if model_name in available_models:
+            return True, model_name
+
+        logger.warning(
+            f"Model {model_name} not found in available models. Using first available model: {available_models[0]}"
+        )
+        return True, available_models[0]
+
+    def get_default_model(self) -> Optional[str]:
+        """Get the default model, falling back to first available if default is not found."""
+        if not self.is_available():
+            return None
+
+        is_valid, model = self.validate_model(self.default_model)
+        if is_valid:
+            return model
+        return None
+
     def summarize(self, text: str, model: Optional[str] = None) -> Optional[str]:
         """Summarize text using Ollama."""
         if not self.is_available():
             logger.warning("Attempted to summarize with Ollama unavailable")
             return None
 
-        model = model or self.default_model
+        # Validate and get the correct model
+        is_valid, valid_model = self.validate_model(model or self.default_model)
+        if not is_valid:
+            logger.error("No valid Ollama models available")
+            return None
+
         prompt = f"{self.prompt}\n\n{text}"
-        logger.info(f"Generating summary using model: {model}")
+        logger.info(f"Generating summary using model: {valid_model}")
         logger.info(f"Input text length: {len(text)} characters")
 
         try:
             response = requests.post(
                 f"{self.url}/api/generate",
-                json={"model": model, "prompt": prompt, "stream": False},
+                json={"model": valid_model, "prompt": prompt, "stream": False},
             )
 
             if response.status_code == 200: