Using threads

I need to write a simple program that uses another thread..
I've done this in C++ builder without any problems, but I seem to be getting something wrong doing this with Delphi..

Here's some of my code:
type
  newthread = class(TThread)
  private
    { Private declarations }
  protected
    procedure Execute; override;
  public
    procedure formrepaint;
  end;

implementation
uses Unit1;

procedure newthread.Execute;
var
cont : boolean;
begin
cont := true;
  while (cont) do
  begin
   Synchronize(Formrepaint);
   if terminated then
    cont := false;
  end;
end;

procedure newthread.formrepaint;
begin
mainform.repaint;
end;

now, the problem I'm having is somewhere at the other end (I think)... in mainform, I have the code
var
  other : newthread;
...
other.create(false);
...
{here I have some code that accesses and does some changes to the mainform}
...
other.destroy;

I'm certain that my mistake is a small and stupid one that would be obvious to someone who know how to use threads in Delphi... please HELP.

The program always crashes where I call the create method... what am I missing????

Thanks in advance...