In order to install the Apache web server that comes with Commander, the install needs to know that port 80 (the standard HTTP service port) is available. If not, it will tell you so. The most common cause for this is having the IIS service installed and running. You will need to remove this by going to:
Programs and Features
Turn Windows Features On and Off
You will then need to disable IIS, or possibly just the World Wide Web Publishing service. The system may ask you to reboot to complete the change.
If that doesn't work, open up a Command window in "Run as administrator" mode and type this command:
netstat -a -b -o | grep ":80"
This will show you a list of all the programs and services that are listening on port 80, as well as their PIDs (process ID's). If it is a program that it is running, it will have to be shutdown. If it is a service, it will have to stopped.
Possibilities for services that may be using port 80 include:
World Wide Web Publishing service
IIS Admin Service
SQL Server Reporting services
Web Deployment Agent service
Run the netstat command shown above to verify that no program or service is listening to port 80, and then repeat the Commander installation.
If you do not wish to disable whatever program or service is currently using port 80, you will have to tell the installer to proceed in the advanced install mode and, when prompted, select a different port of your preference for Commander's web server.