diff --git a/src/BD.WTTS.Client.Avalonia/UI/Views/Windows/MainWindow.axaml.cs b/src/BD.WTTS.Client.Avalonia/UI/Views/Windows/MainWindow.axaml.cs
index 69d09019bba..8cf9bb483ef 100644
--- a/src/BD.WTTS.Client.Avalonia/UI/Views/Windows/MainWindow.axaml.cs
+++ b/src/BD.WTTS.Client.Avalonia/UI/Views/Windows/MainWindow.axaml.cs
@@ -44,10 +44,14 @@ internal bool SetStartDefaultPageName()
         if (NavigationService.Instance.CurrnetPage != null)
             return false;
 
+        var mw2 = IViewModelManager.Instance.MainWindow2;
+        if (mw2 == null)
+            return false;
+
         Type? pageType = null;
         if (!string.IsNullOrEmpty(UISettings.StartDefaultPageName.Value))
         {
-            var tabItems = IViewModelManager.Instance.MainWindow2?.TabItems;
+            var tabItems = mw2?.TabItems;
             if (tabItems == null)
                 return false;
 
diff --git a/src/BD.WTTS.Client/Services/Mvvm/UI/ViewModels/ViewModelManager.cs b/src/BD.WTTS.Client/Services/Mvvm/UI/ViewModels/ViewModelManager.cs
index 0c9247aeea8..0d3522ffc61 100644
--- a/src/BD.WTTS.Client/Services/Mvvm/UI/ViewModels/ViewModelManager.cs
+++ b/src/BD.WTTS.Client/Services/Mvvm/UI/ViewModels/ViewModelManager.cs
@@ -4,8 +4,8 @@ namespace BD.WTTS.Services.Implementation;
 internal sealed class ViewModelManager : ReactiveObject, IViewModelManager
 {
     bool disposedValue;
-    Dictionary<Type, byte[]> viewModelDataCaches = new();
-    Dictionary<Type, ViewModelBase> viewModelCaches = new();
+    ConcurrentDictionary<Type, byte[]> viewModelDataCaches = new();
+    ConcurrentDictionary<Type, ViewModelBase> viewModelCaches = new();
 
     /// <summary>
     /// 获取为当前主窗口提供的数据
@@ -69,7 +69,8 @@ public void Dispose(ViewModelBase viewModel)
         var vmType = viewModel.GetType();
         var value = Serializable.SMP2(vmType, viewModel);
         viewModelDataCaches[vmType] = value;
-        viewModelCaches.Remove(vmType);
+        viewModelDataCaches[vmType] = value;
+        viewModelCaches.TryRemove(vmType, out var _);
     }
 
     void Dispose(bool disposing)