mov2avi on Mac R2011b

When running the following (example) code:

N=10; lambda = 1:N; T=0:0.01:2*pi;
for i=1:N
  y = sin(T*lambda(i));
  plot(T,y)
  F(i) = getframe;
end
movie(F)

I receive the error

 Error using hgMovie
Movie contains uninitialized frames
Error in movie (line 41)
        builtin('hgMovie',varargin{:});
Error in movie_mov2avi_test (line 7)
movie(F)

More importantly, when I try to save the movie as an .avi file I receive the error

Error using avifile/addframe>ValidateFrame (line 286)
Frame must be 184 by 144.

Any advice on what this means and how to rectify the problem would be much appreciated...