Apache2 problem!

I have installed SuSE 9.1 professional on my server to replace another Linux version. Everything seems working fine except some problems I have with Apache. Has anyone encounter the following error message while starting apache2 : Starting httpd2 (prefork) (98)Address already in use: make_sock: could not bind to address 192.168.0.1:80 no listening sockets available, shutting down Unable to open logs I checked to see if the port 80 is used, it is not! Any clue. moussa