Problem when running the 'legend' command under Matlab 2009b

Hi, I am running Matlab 2009b. Since a couple of weeks the legend command does not work anymore, i.e. I do not get any error. However, after having inserted the command legend, the plotted line disappears. For example: x=linspace(-5,5,50); y = sin(x); plot(x,y) works, but after having executed legend('a') the plotted line disappears. Moreover, I cannot plot anything else on the figure until I make a clf or close the figure.

[Walter Roberson]

Please show the output of

which -all legend