diff --git a/__init__.py b/__init__.py
index 40d3fe2..0ca6551 100644
--- a/__init__.py
+++ b/__init__.py
@@ -19,12 +19,64 @@ NODE_DISPLAY_NAME_MAPPINGS.update(IMAGE_NODE_DISPLAY_NAME_MAPPINGS)
 WEB_DIRECTORY = "./js"
 
 try:
+    import asyncio
     import os
+    import shutil
     import subprocess
     import sys
+    import threading
     from aiohttp import web
     from server import PromptServer
 
+    _DUMAS_DIALOG_LOCK = threading.Lock()
+
+    def _dumas_dialog_available():
+        return sys.platform == "win32" and shutil.which("powershell") is not None
+
+    def _dumas_dialog_windows(start_path):
+        ps = (
+            "Add-Type -AssemblyName System.Windows.Forms;"
+            "$r='';"
+            "$o=New-Object System.Windows.Forms.Form;"
+            "$o.TopMost=$true;$o.ShowInTaskbar=$false;$o.FormBorderStyle='None';"
+            "$o.Width=1;$o.Height=1;$o.Opacity=0;$o.StartPosition='CenterScreen';"
+            "$o.Add_Shown({"
+            "$o.Activate();"
+            "$d=New-Object System.Windows.Forms.FolderBrowserDialog;"
+            '$d.Description="Select a folder";$d.ShowNewFolderButton=$true;'
+            "if($env:DUMAS_START){try{$d.SelectedPath=$env:DUMAS_START}catch{}};"
+            "if($d.ShowDialog($o) -eq [System.Windows.Forms.DialogResult]::OK){$script:r=$d.SelectedPath};"
+            "$o.Close()"
+            "});"
+            "[void]$o.ShowDialog();"
+            "[Console]::Out.Write($r)"
+        )
+        env = dict(os.environ)
+        env["DUMAS_START"] = start_path or ""
+        result = subprocess.run(
+            ["powershell", "-NoProfile", "-STA", "-Command", ps],
+            capture_output=True,
+            text=True,
+            timeout=300,
+            env=env,
+            creationflags=0x08000000,
+            check=False,
+        )
+        return (result.stdout or "").strip()
+
+    def _dumas_native_folder_dialog(start_path=""):
+        if not _DUMAS_DIALOG_LOCK.acquire(blocking=False):
+            return None
+        try:
+            if sys.platform == "win32":
+                return _dumas_dialog_windows(start_path)
+            return ""
+        finally:
+            try:
+                _DUMAS_DIALOG_LOCK.release()
+            except Exception:
+                pass
+
     @PromptServer.instance.routes.get("/dumas/api/save_image/file")
     async def dumas_save_image_file(request):
         path = resolve_serve_token(request.query.get("t", ""))
@@ -35,48 +87,17 @@ try:
     @PromptServer.instance.routes.get("/dumas/api/pick_directory")
     async def dumas_pick_directory(request):
         try:
-            if sys.platform != "win32":
-                return web.json_response({"ok": False, "message": "Native folder picker is only available on Windows right now."})
+            if not _dumas_dialog_available():
+                return web.json_response({"ok": False, "message": "Native folder picker is unavailable here.", "unavailable": True})
 
             start_path = str(request.query.get("path", "") or "").strip()
             if start_path and not os.path.isdir(start_path):
                 start_path = ""
 
-            ps_lines = [
-                "Add-Type -AssemblyName System.Windows.Forms",
-                "$dialog = New-Object System.Windows.Forms.FolderBrowserDialog",
-                '$dialog.Description = "Select a folder"',
-                "$dialog.ShowNewFolderButton = $true",
-            ]
-            if start_path:
-                escaped = start_path.replace("'", "''")
-                ps_lines.append(f"$dialog.SelectedPath = '{escaped}'")
-            ps_lines.extend(
-                [
-                    "if ($dialog.ShowDialog() -eq [System.Windows.Forms.DialogResult]::OK) {",
-                    "  [Console]::OutputEncoding = [System.Text.Encoding]::UTF8",
-                    "  Write-Output $dialog.SelectedPath",
-                    "}",
-                ]
-            )
-            command = "; ".join(ps_lines)
-            result = subprocess.run(
-                [
-                    "powershell",
-                    "-NoProfile",
-                    "-STA",
-                    "-ExecutionPolicy",
-                    "Bypass",
-                    "-Command",
-                    command,
-                ],
-                capture_output=True,
-                text=True,
-                encoding="utf-8",
-                errors="replace",
-                check=False,
-            )
-            selected = (result.stdout or "").strip()
+            loop = asyncio.get_running_loop()
+            selected = await loop.run_in_executor(None, _dumas_native_folder_dialog, start_path)
+            if selected is None:
+                return web.json_response({"ok": False, "busy": True})
             if not selected:
                 return web.json_response({"ok": False, "cancelled": True})
             return web.json_response({"ok": True, "path": selected})