diff --git a/src/Microsoft.VisualBasic.Forms/src/Microsoft/VisualBasic/ApplicationServices/WindowsFormsApplicationBase.vb b/src/Microsoft.VisualBasic.Forms/src/Microsoft/VisualBasic/ApplicationServices/WindowsFormsApplicationBase.vb
index f03e1f494e7..5a47f81fb98 100644
--- a/src/Microsoft.VisualBasic.Forms/src/Microsoft/VisualBasic/ApplicationServices/WindowsFormsApplicationBase.vb
+++ b/src/Microsoft.VisualBasic.Forms/src/Microsoft/VisualBasic/ApplicationServices/WindowsFormsApplicationBase.vb
@@ -11,6 +11,8 @@ Imports System.IO.Pipes
 Imports System.Reflection
 Imports System.Runtime.InteropServices
 Imports System.Security
+Imports System.Security.Cryptography
+Imports System.Text
 Imports System.Threading
 Imports System.Windows.Forms
 Imports Microsoft.VisualBasic.CompilerServices
@@ -354,7 +356,7 @@ Namespace Microsoft.VisualBasic.ApplicationServices
                         Dim awaitable = SendSecondInstanceArgsAsync(ApplicationInstanceID, commandLine, cancellationToken:=tokenSource.Token).ConfigureAwait(False)
                         awaitable.GetAwaiter().GetResult()
                     Catch ex As Exception
-                        Throw New CantStartSingleInstanceException()
+                        Throw New CantStartSingleInstanceException($"{GetResourceString(SR.AppModel_SingleInstanceCantConnect)}: {ApplicationInstanceID}")
                     End Try
                 End If
             End If 'Single-Instance application
@@ -1006,28 +1008,35 @@ Namespace Microsoft.VisualBasic.ApplicationServices
 
         ''' <summary>
         ''' Generates the name for the remote singleton that we use to channel multiple instances
-        ''' to the same application model thread.
+        ''' to the same application model thread for the current user.
         ''' </summary>
         ''' <returns>A string unique to the application that should be the same for versions of
         '''  the application that have the same Major and Minor Version Number
         ''' </returns>
         ''' <remarks>If GUID Attribute does not exist fall back to unique ModuleVersionId</remarks>
-        Private Shared Function GetApplicationInstanceID(ByVal Entry As Assembly) As String
-
-            Dim guidAttrib As GuidAttribute = Entry.GetCustomAttribute(Of GuidAttribute)()
-
-            If guidAttrib IsNot Nothing Then
-
-                Dim version As Version = Entry.GetName.Version
-
+        Private Shared Function GetApplicationInstanceID(entry As Assembly) As String
+            Dim guidAttribute As GuidAttribute = entry.GetCustomAttribute(Of GuidAttribute)()
+            Dim currentUserSID As String = Principal.WindowsIdentity.GetCurrent().User.Value
+            Dim location As String = entry.Location
+            Dim pathGuid As Guid = GetFilePathAsGuid(location)
+            If guidAttribute IsNot Nothing Then
+                Dim version As Version = entry.GetName.Version
                 If version IsNot Nothing Then
-                    Return $"{guidAttrib.Value}{version.Major}.{version.Minor}"
+                    Return $"{pathGuid}-{guidAttribute.Value}{version.Major}.{version.Minor}-{currentUserSID}"
                 Else
-                    Return guidAttrib.Value
+                    Return $"{pathGuid}-{guidAttribute.Value}-{currentUserSID}"
                 End If
             End If
 
-            Return Entry.ManifestModule.ModuleVersionId.ToString()
+            Return $"{pathGuid}-{entry.ManifestModule.ModuleVersionId}-{currentUserSID}"
+        End Function
+
+#Disable Warning CA5351 ' We want speed over collision resistance.
+        Private Shared Function GetFilePathAsGuid(filePath As String) As Guid
+            Dim filePathBytes As Byte() = Encoding.UTF8.GetBytes(filePath)
+            Dim hashBytes As Byte() = MD5.HashData(filePathBytes)
+            Return New Guid(hashBytes)
         End Function
+#Enable Warning CA5351
     End Class
 End Namespace
diff --git a/src/Microsoft.VisualBasic/tests/UnitTests/Microsoft/VisualBasic/ApplicationServices/WindowsFormsApplicationBaseTests.cs b/src/Microsoft.VisualBasic/tests/UnitTests/Microsoft/VisualBasic/ApplicationServices/WindowsFormsApplicationBaseTests.cs
index 8ee2c982c4f..392d80cc100 100644
--- a/src/Microsoft.VisualBasic/tests/UnitTests/Microsoft/VisualBasic/ApplicationServices/WindowsFormsApplicationBaseTests.cs
+++ b/src/Microsoft.VisualBasic/tests/UnitTests/Microsoft/VisualBasic/ApplicationServices/WindowsFormsApplicationBaseTests.cs
@@ -15,15 +15,22 @@ private static string GetAppID(Assembly assembly)
         return testAccessor.Dynamic.GetApplicationInstanceID(assembly);
     }
 
+    private static Guid GetFilePathAsGuid(string filePath)
+    {
+        var testAccessor = typeof(WindowsFormsApplicationBase).TestAccessor();
+        return testAccessor.Dynamic.GetFilePathAsGuid(filePath);
+    }
+
     [Fact]
     public void GetApplicationInstanceID()
     {
         var assembly = typeof(WindowsFormsApplicationBaseTests).Assembly;
-        string expectedId = assembly.ManifestModule.ModuleVersionId.ToString();
+        string currentUserSID = System.Security.Principal.WindowsIdentity.GetCurrent().User.Value;
+        string expectedId = $"{GetFilePathAsGuid(assembly.Location)}-{assembly.ManifestModule.ModuleVersionId}-{currentUserSID}";
         Assert.Equal(expectedId, GetAppID(assembly));
     }
 
-    private static string GetUniqueIDFromAssembly(string guid, Version version)
+    private static Assembly CreateDynamicAssembly(string guid, Version version)
     {
         CustomAttributeBuilder attributeBuilder = new(
             typeof(GuidAttribute).GetConstructor([typeof(string)]), new[] { guid });
@@ -32,27 +39,41 @@ private static string GetUniqueIDFromAssembly(string guid, Version version)
             AssemblyBuilderAccess.RunAndCollect,
             new[] { attributeBuilder });
         assemblyBuilder.DefineDynamicModule(Guid.NewGuid().ToString());
-        return GetAppID(assemblyBuilder);
+        return assemblyBuilder;
     }
 
     [Fact]
     public void GetApplicationInstanceID_GuidAttribute()
     {
         string guid = Guid.NewGuid().ToString();
-        Assert.Equal($"{guid}1.2", GetUniqueIDFromAssembly(guid, new Version(1, 2, 3, 4)));
+        string currentUserSID = System.Security.Principal.WindowsIdentity.GetCurrent().User.Value;
+        Version version = new Version(1, 2, 3, 4);
+        var assembly = CreateDynamicAssembly(guid, version);
+        string location = assembly.Location;
+        Guid expectedPathGuid = GetFilePathAsGuid(location);
+        Assert.Equal($"{expectedPathGuid}-{guid}{version.Major}.{version.Minor}-{currentUserSID}", GetAppID(assembly));
     }
 
     [Fact]
     public void GetApplicationInstanceID_GuidAttributeNewVersion()
     {
         string guid = Guid.NewGuid().ToString();
-        Assert.Equal($"{guid}0.0", GetUniqueIDFromAssembly(guid, new Version()));
+        string currentUserSID = System.Security.Principal.WindowsIdentity.GetCurrent().User.Value;
+        Version version = new Version();
+        var assembly = CreateDynamicAssembly(guid, version);
+        string location = assembly.Location;
+        Guid expectedPathGuid = GetFilePathAsGuid(location);
+        Assert.Equal($"{expectedPathGuid}-{guid}0.0-{currentUserSID}", GetAppID(assembly));
     }
 
     [Fact]
     public void GetApplicationInstanceID_GuidAttributeNullVersion()
     {
         string guid = Guid.NewGuid().ToString();
-        Assert.Equal($"{guid}0.0", GetUniqueIDFromAssembly(guid, version: null));
+        string currentUserSID = System.Security.Principal.WindowsIdentity.GetCurrent().User.Value;
+        var assembly = CreateDynamicAssembly(guid, null);
+        string location = assembly.Location;
+        Guid expectedPathGuid = GetFilePathAsGuid(location);
+        Assert.Equal($"{expectedPathGuid}-{guid}0.0-{currentUserSID}", GetAppID(assembly));
     }
 }