I\'m using Windows 7 64 bit. Each time, I\'m using plot function, plot windows will shows and draws successfully, but after that it stops responding and must shut down it.>
I have similar symptoms using octave 4.2 when running your code (Cannot close plot windows, plot takes time to appear). When statements don't end with semicolon (;) the command and result will be printed in command window. It SEEMS to me that the command window halts interpretation of code and wait for user to press a valid key (f,b,q) to contunure or abort execution. The halt point is dependent on previously executed code and size of command window, therefore the intermittent nature of these symptoms.
Solution:
Option 1: Go to command window and keep pressing f (forward)
Option 2: Use semicolon to terminate statements
x = linspace(0,1,10);
y = x.^2;
plot(x,y);
Option 3: Fiddle with some command window settings
Hope it helps