diff -prudN e:\Wine\dlls\urlmon/bindprot.c e:\reactos\dll\win32\urlmon/bindprot.c
--- e:\Wine\dlls\urlmon/bindprot.c	2014-04-04 14:12:42.439519600 +0100
+++ e:\reactos\dll\win32\urlmon/bindprot.c	2014-04-11 16:18:48.958227500 +0100
@@ -83,36 +80,14 @@ static LRESULT WINAPI notif_wnd_proc(HWN
     return DefWindowProcW(hwnd, msg, wParam, lParam);
 }
 
-static const WCHAR wszURLMonikerNotificationWindow[] =
-    {'U','R','L',' ','M','o','n','i','k','e','r',' ',
-     'N','o','t','i','f','i','c','a','t','i','o','n',' ','W','i','n','d','o','w',0};
-
-static ATOM notif_wnd_class;
-
-static BOOL WINAPI register_notif_wnd_class(INIT_ONCE *once, void *param, void **context)
-{
-    static WNDCLASSEXW wndclass = {
-        sizeof(wndclass), 0, notif_wnd_proc, 0, 0,
-        NULL, NULL, NULL, NULL, NULL,
-        wszURLMonikerNotificationWindow, NULL
-    };
-
-    wndclass.hInstance = hProxyDll;
-    notif_wnd_class = RegisterClassExW(&wndclass);
-    return TRUE;
-}
-
-void unregister_notif_wnd_class(void)
-{
-    if(notif_wnd_class)
-        UnregisterClassW(MAKEINTRESOURCEW(notif_wnd_class), hProxyDll);
-}
-
 HWND get_notif_hwnd(void)
 {
+    static ATOM wnd_class = 0;
     tls_data_t *tls_data;
 
-    static INIT_ONCE init_once = INIT_ONCE_STATIC_INIT;
+    static const WCHAR wszURLMonikerNotificationWindow[] =
+        {'U','R','L',' ','M','o','n','i','k','e','r',' ',
+         'N','o','t','i','f','i','c','a','t','i','o','n',' ','W','i','n','d','o','w',0};
 
     tls_data = get_tls_data();
     if(!tls_data)
@@ -123,11 +98,23 @@ HWND get_notif_hwnd(void)
         return tls_data->notif_hwnd;
     }
 
-    InitOnceExecuteOnce(&init_once, register_notif_wnd_class, NULL, NULL);
-    if(!notif_wnd_class)
-        return NULL;
+    if(!wnd_class) {
+        static WNDCLASSEXW wndclass = {
+            sizeof(wndclass), 0,
+            notif_wnd_proc, 0, 0,
+            NULL, NULL, NULL, NULL, NULL,
+            wszURLMonikerNotificationWindow,
+            NULL
+        };
 
-    tls_data->notif_hwnd = CreateWindowExW(0, MAKEINTRESOURCEW(notif_wnd_class),
+        wndclass.hInstance = hProxyDll;
+
+        wnd_class = RegisterClassExW(&wndclass);
+        if (!wnd_class && GetLastError() == ERROR_CLASS_ALREADY_EXISTS)
+            wnd_class = 1;
+    }
+
+    tls_data->notif_hwnd = CreateWindowExW(0, wszURLMonikerNotificationWindow,
             wszURLMonikerNotificationWindow, 0, 0, 0, 0, 0, HWND_MESSAGE,
             NULL, hProxyDll, NULL);
     if(tls_data->notif_hwnd)

diff -prudN e:\Wine\dlls\urlmon/urlmon_main.c e:\reactos\dll\win32\urlmon/urlmon_main.c
--- e:\Wine\dlls\urlmon/urlmon_main.c	2014-04-04 14:12:42.460533100 +0100
+++ e:\reactos\dll\win32\urlmon/urlmon_main.c	2014-04-11 16:19:12.473179000 +0100
@@ -139,7 +127,6 @@ static void process_detach(void)
 
     free_session();
     free_tls_list();
-    unregister_notif_wnd_class();
 }
 
 /***********************************************************************

diff -prudN e:\Wine\dlls\urlmon/urlmon_main.h e:\reactos\dll\win32\urlmon/urlmon_main.h
--- e:\Wine\dlls\urlmon/urlmon_main.h	2014-04-04 14:12:42.461533700 +0100
+++ e:\reactos\dll\win32\urlmon/urlmon_main.h	2014-04-11 16:19:21.822446700 +0100
@@ -225,7 +236,6 @@ typedef struct {
 
 tls_data_t *get_tls_data(void) DECLSPEC_HIDDEN;
 
-void unregister_notif_wnd_class(void) DECLSPEC_HIDDEN;
 HWND get_notif_hwnd(void) DECLSPEC_HIDDEN;
 void release_notif_hwnd(HWND) DECLSPEC_HIDDEN;