[users@httpd] apache port num. problem

[Mr. Steve Burrus]

i need some assistance with always getting this when I try to 
start/activate apache. Apparently it is a port address number problem.

"(OS 10048)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 sockets available, shutting down
Unable to open logs"
Incidentally I have in the apache config file [httpd.conf] the line 
"Listen [my ip address  port number]:80"