I cant start Apache

[eposey]

When i start Apache on XAMPP i get this error at the bottom:

12:59:03 PM [Apache] Problem detected!
12:59:03 PM [Apache] Port 80 in use by "Unable to open process" with PID 4!
12:59:03 PM [Apache] Apache WILL NOT start without the configured ports free!
12:59:03 PM [Apache] You need to uninstall/disable/reconfigure the blocking application
12:59:03 PM [Apache] or reconfigure Apache and the Control Panel to listen on a different port

Can anybody fix this?

[Nobbie]

Enter "Port 80 in use by "Unable to open process" with PID 4!" into Google.