Usually when the installation hangs, it is caused by a conflict with other software on the computer. The most likely culprit is Anti Virus software, but the problem can be caused by other real time file scanning software as well.
I have seen some firewalls that include software to scan any file that is created on the system, it is this sort of activity that causes the installation to hang.
Try disabling your anti virus software or any other real time file scanning software you may have. Then try installing the extensions again.