diff --git a/src/spice2x/games/iidx/iidx.cpp b/src/spice2x/games/iidx/iidx.cpp
index b1f05d4..9fe0d6f 100644
--- a/src/spice2x/games/iidx/iidx.cpp
+++ b/src/spice2x/games/iidx/iidx.cpp
@@ -82,6 +82,7 @@ namespace games::iidx {
     bool IIDXIO_LED_TICKER_READONLY = false;
     std::mutex IIDX_LED_TICKER_LOCK;
     bool IIDX_TDJ_MONITOR_WARNING = false;
+    iidx_aio_emulation_state CURRENT_IO_EMULATION_STATE = iidx_aio_emulation_state::unknown;
 
     // io
     static bool HAS_LIBAIO; // this is how we detect iidx27+
@@ -453,7 +454,7 @@ namespace games::iidx {
         }
 
         // windowed subscreen, enabled by default, unless turned off by user
-        if (GRAPHICS_WINDOWED && !options->at(launcher::Options::spice2x_IIDXNoSub).value_bool()) {
+        if (GRAPHICS_WINDOWED && !options->at(launcher::Options::spice2x_IIDXNoSub).value_bool() && TDJ_MODE) {
             GRAPHICS_IIDX_WSUB = true;
         }
 
@@ -934,6 +935,8 @@ namespace games::iidx {
             return;
         }
 
+        CURRENT_IO_EMULATION_STATE = state;
+
         // log_warning below could be turned into log_fatal in the future once we gain confidence
         // that this isn't triggering when it's not supposed to
         if (state == iidx_aio_emulation_state::bi2a_com2 && TDJ_MODE) {
diff --git a/src/spice2x/games/iidx/iidx.h b/src/spice2x/games/iidx/iidx.h
index 997d1a7..2178901 100644
--- a/src/spice2x/games/iidx/iidx.h
+++ b/src/spice2x/games/iidx/iidx.h
@@ -11,6 +11,12 @@
 
 namespace games::iidx {
 
+    enum class iidx_aio_emulation_state {
+        unknown,
+        bi2a_com2,
+        bi2x_hook
+    };
+
     // settings
 
     extern bool FLIP_CAMS;
@@ -38,6 +44,7 @@ namespace games::iidx {
     constexpr int IIDX_TAPELED_TOTAL = 17;
     // data mapping
     extern tapeledutils::tape_led TAPELED_MAPPING[IIDX_TAPELED_TOTAL];
+    extern iidx_aio_emulation_state CURRENT_IO_EMULATION_STATE;
 
     class IIDXGame : public games::Game {
     public:
@@ -64,9 +71,5 @@ namespace games::iidx {
     bool is_tdj_fhd();
     void apply_audio_hacks();
 
-    enum class iidx_aio_emulation_state {
-        bi2a_com2,
-        bi2x_hook
-    };
     void update_io_emulation_state(iidx_aio_emulation_state state);
 }
diff --git a/src/spice2x/overlay/windows/generic_sub.cpp b/src/spice2x/overlay/windows/generic_sub.cpp
index b20df4d..c5244c6 100644
--- a/src/spice2x/overlay/windows/generic_sub.cpp
+++ b/src/spice2x/overlay/windows/generic_sub.cpp
@@ -85,10 +85,12 @@ namespace overlay::windows {
     }
 
     void GenericSubScreen::touch_transform(const ImVec2 xy_in, LONG *x_out, LONG *y_out) {}
+    void GenericSubScreen::check_for_errors() {}
 
     void GenericSubScreen::build_content() {
         this->flags |= ImGuiWindowFlags_NoBackground;
         
+        check_for_errors();
         if (this->disabled_message.has_value()) {
             this->draws_window = true;
             this->flags &= ~ImGuiWindowFlags_NoBackground;
diff --git a/src/spice2x/overlay/windows/generic_sub.h b/src/spice2x/overlay/windows/generic_sub.h
index 0ee53f8..ae39bfb 100644
--- a/src/spice2x/overlay/windows/generic_sub.h
+++ b/src/spice2x/overlay/windows/generic_sub.h
@@ -31,6 +31,7 @@ namespace overlay::windows {
 
     protected:
         virtual void touch_transform(const ImVec2 xy_in, LONG *x_out, LONG *y_out);
+        virtual void check_for_errors();
         ImVec2 overlay_content_top_left;
         ImVec2 overlay_content_size;
         std::optional<std::string> disabled_message = std::nullopt;
diff --git a/src/spice2x/overlay/windows/iidx_seg.cpp b/src/spice2x/overlay/windows/iidx_seg.cpp
index 0cf37e1..02d9708 100644
--- a/src/spice2x/overlay/windows/iidx_seg.cpp
+++ b/src/spice2x/overlay/windows/iidx_seg.cpp
@@ -14,6 +14,7 @@ namespace overlay::windows {
 
     static const size_t TICKER_SIZE = 9;
     static const ImVec4 DARK_GRAY(0.1f, 0.1f, 0.1f, 1.f);
+    static const ImVec4 YELLOW(1.f, 1.f, 0.f, 1.f);
     static const ImVec4 RED(1.f, 0.f, 0.f, 1.f);
     static const float PADDING_Y = 8.f;
     static const float PADDING_X = 4.f;
@@ -91,6 +92,23 @@ namespace overlay::windows {
     }
 
     void IIDXSegmentDisplay::build_content() {
+
+        // explicitly check if TDJ I/O is enabled to account for the fact that I/O emulation may be
+        // disabled
+        if (games::iidx::CURRENT_IO_EMULATION_STATE == games::iidx::iidx_aio_emulation_state::bi2x_hook) {
+            ImGui::TextUnformatted("");
+            ImGui::TextColored(
+                YELLOW,
+                "%s",
+                "Invalid I/O mode; DLL is configured for TDJ I/O!\n"
+                "Enable -iidxtdj if you want TDJ subscreen overlay.");
+            ImGui::TextUnformatted("");
+            if (ImGui::Button("Close")) {
+                this->set_active(false);
+            }
+            return;
+        }
+
         char input_ticker[TICKER_SIZE];
 
         // get ticker content from game
diff --git a/src/spice2x/overlay/windows/iidx_sub.cpp b/src/spice2x/overlay/windows/iidx_sub.cpp
index 4c01684..4f8ea5a 100644
--- a/src/spice2x/overlay/windows/iidx_sub.cpp
+++ b/src/spice2x/overlay/windows/iidx_sub.cpp
@@ -12,11 +12,9 @@ namespace overlay::windows {
         this->title = "IIDX TDJ Subscreen";
 
         if (GRAPHICS_IIDX_WSUB) {
-            this->disabled_message =
-                "Close this overlay and use the second window (ALT+TAB).\n"
-                "If you don't see the window, double check your DLL type and apply TDJ I/O patches as needed.";
+            this->disabled_message = "Close this overlay and use the second window. (try ALT+TAB)";
         } else if (games::iidx::IIDX_TDJ_MONITOR_WARNING) {
-            this->disabled_message = "TDJ mode subscreen overlay is not compatible with -monitor option";
+            this->disabled_message = "TDJ mode subscreen overlay is not compatible with -monitor option.";
         }
 
         float size = 0.5f;
@@ -44,6 +42,18 @@ namespace overlay::windows {
             ImGui::GetIO().DisplaySize.y - this->init_size.y - (ImGui::GetFrameHeight() / 2));
     }
 
+    void IIDXSubScreen::check_for_errors() {
+        if (games::iidx::CURRENT_IO_EMULATION_STATE ==
+            games::iidx::iidx_aio_emulation_state::bi2a_com2) {
+
+            // explicitly check if LDJ I/O is enabled (as opposed to checking if NOT TDJ I/O)
+            // to account for the fact that I/O emulation may be disabled
+            this->disabled_message =
+                "LDJ I/O detected; TDJ mode subscreen overlay requires TDJ I/O.\n"
+                "Ensure you apply applicable TDJ I/O patches, or run with TDJ DLL.";
+        }
+    }
+
     void IIDXSubScreen::touch_transform(const ImVec2 xy_in, LONG *x_out, LONG *y_out) {
         if (!this->get_active()) {
             return;
diff --git a/src/spice2x/overlay/windows/iidx_sub.h b/src/spice2x/overlay/windows/iidx_sub.h
index adb897d..7d77cae 100644
--- a/src/spice2x/overlay/windows/iidx_sub.h
+++ b/src/spice2x/overlay/windows/iidx_sub.h
@@ -12,6 +12,7 @@ namespace overlay::windows {
 
     protected:
         void touch_transform(const ImVec2 xy_in, LONG *x_out, LONG *y_out) override;
+        void check_for_errors() override;
     };
 }