right click on command prompt titlebar and click on properties. click on font and here change the font size.
I have this kind of issue from a while....but no remain small window.Sometime command window is normal.
Instead of editing the properties of cmd itself, you could always use a batch file to open the command prompt and have it run with custom settings... MODE CON: cols=21 lines=20
i have still problem every time i open command line is small i go to properties change font and layout but after restart it came back to small :_(