Explorer Error

[Leite33]

Hi!!
I have made an explorer in C++Borland Builder 6...I used components DriveComboBox,DirectoryListBox and FileListBox and i connnect them.... But when i go to other drives than 'c' with DriveComboBox that dont have anything inside(empty) it brings me an expection: "EInOutError with message I/O error 21". I used the above code to correct it and bring a message to user that the drive is empty but no luck.... If anyone have any ideas on the above code or some new please send some help......

 TDriveComboBox *Control = (TDriveComboBox*)Sender;
   AnsiString strRoot = (AnsiString)(char)Control->Drive+":\\";
   DWORD dwOldErrorMode;

   try
    {
      dwOldErrorMode = SetErrorMode(SEM_FAILCRITICALERRORS);
      try
       {
         DirectoryListBox1->Drive = Control->Drive;

         if(!DirectoryExists(strRoot))
          throw EInOutError("");
       }
      catch(EInOutError &Error)
       {
         MessageDlg("Drive not ready!",mtError,TMsgDlgButtons()<<mbOK,0);
         Control->Drive = 'C';
       }
    }
   __finally
    {
      SetErrorMode(dwOldErrorMode);
    }