Today I was unable to start Apache using a new install of XAMPP. A quick netstat -o in cmd showed something was blocking port 80.

After about an hour of searching, I discovered that port 80 was in use by Skype. No kidding. There is an advanced setting in skype to “Use port 80 and 443 as alternate incoming connections.” If this is checked (which it is by default) then a service is started on port 80 that blocks Apache. Ungh for bad ideas and even worse defaults.