Stack overflow

If you receive that exception, and you are using something like:

...
var
Buffer: array [0..MAX_SIZE] of Char;

Than MAX_SIZE is too big, because Char can take small mount of data.

Use better something like this:

{
The following example opens a file of your choice and reads
the entire file into a dynamically allocated buffer. The
buffer and the size of the file are then passed to a routine
that processes the text, and finally the dynamically
allocated buffer is freed and the file is closed.
} 
procedure TForm1.Button1Click(Sender: TObject);
var
  F: file;
  Size: Integer;
  Buffer: PChar;
begin
  if OpenDialog1.Execute then
  begin
    AssignFile(F, OpenDialog1.FileName);
    Reset(F, 1);
    try
      Size := FileSize(F);
      GetMem(Buffer, Size);
      try
        BlockRead(F, Buffer^, Size);
        Memo1.Lines.Add(Buffer);
      finally
        FreeMem(Buffer);
      end;
    finally
      CloseFile(F);
    end;
  end;
end;

That code is taken from Delphi help, system.FreeMem function.