Public Class Frm_Main
 
    Private Sub Cmd_File_erstellen_Click(ByVal sender As System.Object, ByVal e _
      As System.EventArgs) Handles Cmd_File_erstellen.Click
        My.Computer.FileSystem.WriteAllText( _
        Testprogramm.My.Application.Info.DirectoryPath & "\test.txt", "Hallo" & _
        "Welt", False)
        MsgBox("Datei hier " & Testprogramm.My.Application.Info.DirectoryPath & _
        "\test.txt" & " erstellt")
    End Sub
 
    Private Sub Cmd_Datei_kopieren_Click(ByVal sender As System.Object, ByVal e _
      As System.EventArgs) Handles Cmd_Datei_kopieren.Click
        My.Computer.FileSystem.CopyFile( _
        Testprogramm.My.Application.Info.DirectoryPath & "\test.txt", _
        Testprogramm.My.Application.Info.DirectoryPath & "\testneu.txt")
    End Sub
End Class

Zitat:

See the end of this message for details on invoking just-in-time (JIT) debugging instead of this dialog box. ************** Exception Text ************** System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. at System.Security.CodeAccessSecurityEngine.Check(Object demand, StackCrawlMark& stackMark, Boolean isPermSet) at System.Security.CodeAccessPermission.Demand() at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy) at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options) at System.IO.StreamWriter.CreateFile(String path, Boolean append) at System.IO.StreamWriter..ctor(String path, Boolean append, Encoding encoding, Int32 bufferSize) at System.IO.StreamWriter..ctor(String path, Boolean append, Encoding encoding) at Microsoft.VisualBasic.FileIO.FileSystem.WriteAllText(String file, String text, Boolean append, Encoding encoding) at Microsoft.VisualBasic.MyServices.FileSystemProxy.WriteAllText(String file, String text, Boolean append) at Testprogramm.Frm_Main.Cmd_File_erstellen_Click(Object sender, EventArgs e) at System.Windows.Forms.Control.OnClick(EventArgs e) at System.Windows.Forms.Button.OnClick(EventArgs e) at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent) at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ButtonBase.WndProc(Message& m) at System.Windows.Forms.Button.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) The action that failed was: Demand The type of the first permission that failed was: System.Security.Permissions.FileIOPermission The Zone of the assembly that failed was: Intranet