Port 80 is already used by another program in windows

This may happens in Windows machines while installing Apache.

This because of the port may be used by some other program like Skype or default os service. To resolve this try the below ways:

• Disable HTTP.sys driver that was started by some of the Windows inbuilt applications
• Disable the HTTP in registry under the path "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HTTP"