Though in the past week I had two freeze-ups of Audacity requiring a reboot of Win-7 to remedy. It probably has to do with running VLC Media Player beforehand, or a file being open or playing in VLC. Not sure of the exact conditions. It could have been from trying to start a second session of Audacity before the first session rendered itself on the screen.
You can have multiple Audacity windows, but not multiple instances of Audacity running at once.
If Audacity(s) , or any other program, causes Windows to freeze,
rather than reboot , go to Windows “Task Manager” , (Ctrl+Alt+Delete) , and end the problematic program [“end process”]…