Command window freezing by matrices

I have a problem by giving new matrices in Octave.
When I type a matrix on this way [1 2 3; 4 5 6; then the command window is freezing over second coma “;”. But I can use with the rest windows.
But when I type a matrix in this form [ ; ; ] and after I type the number I don’t have any problem. Moreover after I give this first matrix I can type 3 times 3 matrices on the way [ 1 2 3; 4 5 6; . But I have problem with bigger matrices. When I type a matrix with four rows then I got the same problem.
Do you have any problem what cause this problem?

My system

I’m not sure if I correctly understand what you are describing.
Maybe you are confused by the fact that Octave continues the input until every token is closed:

>> a = [1 2 3; 4 5 6;
7 8 9]
a =

   1   2   3
   4   5   6
   7   8   9

Note that the input continues on the second line (7 8 9]).

If you want to abort input, you can use Ctrl+C.

Thanks for the answer. But I think I was not enough clear. I can not type any symbol to the Command Window in this case:

It is frozen. I can not type to the next line.
But I can work in this case:

Sorry, I still don’t understand.
Which keys are you pressing in which order? What are you expecting that should happen? What is happening instead?

Sorry, for it.
When I press keys [ 1 2 3; 4 5 6; the cursor has change a moment to a CD symbol and the Command Window is freezen. I can not type anything in this Window.
When I press keys [ ; ; ] and after 1 2 3 4 5 6 7 8 9 I don’t have any problem.

Do I understand correctly that you do not press the return or enter key before the command window freezes?
Are you working with a non-English keyboard layout? If so, is it possible that you are entering some non-ASCII character (maybe by accident)?
I’m not sure if an English keyboard layout is “save” either. Is it possible to enter non-ASCII characters with that layout?
I’m working with a German keyboard layout and have also seen the command window blocking after entering some characters (I believe some Alt Gr+key combinations — Alt Gr+Ä did it just now).
The background for this is that the Windows console (which is used for the command window in Octave) crashes for certain non-ASCII inputs.
There was an open bug report about this on savannah (that identified which bytes are the culprit IIRC). But I can’t find it at the moment.

There also have been some experiments to replace the command windows with something that doesn’t rely on the Windows console. I’d expect that these errors would disappear if/when this is implemented.

I understand that this isn’t very satisfactory. But for now it’s best to avoid to (accidentally?) enter non-ASCII characters.

Yes, you understand correctly I do not press the return or enter key.
Yes, I’m working a Hungarian keyboard layout. Some of my students met with the same problem. They are using Hungarian keyboard as well. Perhaps we are entering some non-ASCII accident (but I don’t think so). I don’t understand why matter the order of pressing keys. We have problem only after the second symbol ;

I’m asking because it might be important which keypress triggers this bug. If I correctly understand, a semicolon is entered with an Alt Gr+key combination on a Hungarian keyboard. Are you sure you are only pressing these keys to trigger the bug? Or could it be possible that some other (combination of) keys triggers this?
What is the first key (combination) you are pressing immediately after the last semicolon that still appears in the command window?

I think I found the report I thought of that might be causing the issues you are seeing:
GNU Octave - Bugs: bug #59495, Entering certain glyphs might… [Savannah]

Thank you very much for your effort!
Perhaps you are right. I have problem only if I give numbers on numeric keypad. More precisely if I press Alt Gr + a number on key pad then the command window being irresponsible to any further input.