I had the same problem with Google Voice and Video:
Your computer can't be restarted now, because software is being installed.
Google Voice and Video is being installed. Interrupting the install may damage your computer. You can restart when the install is complete.
First of all, find the process PID in Activity Monitor or using
ps wuax in Terminal e.g. by:
ps wuax | grep install.
If you can't find it, try to move the window as fast as possible and check which process takes CPU time.
In Activity Monitor you can actually take a Sample of the process what's doing.
Or by debugging it from Terminal
sudo dtruss -fp 1234
If this does nothing, try to send hang up signal first to the process what it would do by (replace 1234 with your Process ID number):
sudo kill -HUP 1234
then if nothing happens, try to kill it softly by:
sudo kill 1234
if it's still not killed, then try it hardly by:
sudo kill -9 1234
Other method is to use
xkill if you've this tool installed:
- Click on the window which you want to kill.
Another easy method is to press Alt+CMD+Esc, then popup should appear, and you can select and kill the process.