New Socket Problem

[AEBoy]

I finally got the PHP and SSI to work and now my server won't even start up. It keeps saying "Only one usage of each socket address (protocol/network address/ port) is normally permitted. : make_sock: could not bind to address 0.0.0.0:80 no listening socket is available, shutting down"

I have no idea what this means, I haven't changed anything in my network settings in months and prior to starting my computer the web server was working. There are no other web servers running on the network either.