diff --git a/js/app.js b/js/app.js
index aed6e39..00bb14d 100644
--- a/js/app.js
+++ b/js/app.js
@@ -7708,7 +7708,20 @@ async function init() {
             const original = btn.textContent;
             btn.textContent = 'Press combo… (Esc to cancel)';
 
+            // A combo already owned by another app via RegisterHotKey is
+            // swallowed by Windows — it is delivered to that app, never to us,
+            // so the capture would wait forever with no explanation. It also
+            // preventDefaults every keystroke while armed, so an abandoned
+            // capture freezes the app's keyboard. Time out and say why.
+            const timer = setTimeout(() => {
+                finish(true);
+                toast('No combo captured. If you did press one, another app ' +
+                      'already owns it — Windows routes it there and we never ' +
+                      'see it. Try a different combo.', 'warning');
+            }, 10000);
+
             function finish(restore) {
+                clearTimeout(timer);
                 btn.dataset.capturing = '';
                 btn.classList.remove('is-capturing');
                 document.removeEventListener('keydown', onKey, true);