port 80 error

[Benrabe]

11:46:40 PM [main] Initializing Control Panel
11:46:40 PM [main] Windows Version: Windows 7 Professional SP1 64-bit
11:46:40 PM [main] XAMPP Version: 1.8.2
11:46:40 PM [main] Control Panel Version: 3.2.1 [ Compiled: May 7th 2013 ]
11:46:40 PM [main] Running with Administrator rights - good!
11:46:40 PM [main] XAMPP Installation Directory: "c:\xampp\"
11:46:40 PM [main] Checking for prerequisites
11:46:54 PM [main] All prerequisites found
11:46:54 PM [main] Initializing Modules
11:46:55 PM [Apache] Problem detected!
11:46:55 PM [Apache] Port 80 in use by "Unable to open process" with PID 4!
11:46:55 PM [Apache] Apache WILL NOT start without the configured ports free!
11:46:55 PM [Apache] You need to uninstall/disable/reconfigure the blocking application
11:46:55 PM [Apache] or reconfigure Apache and the Control Panel to listen on a different port
11:46:55 PM [filezilla] Problem detected!
11:46:55 PM [filezilla] Port 21 in use by ""C:\Program Files (x86)\FileZilla Server\FileZilla Server.exe""!
11:46:55 PM [filezilla] FileZilla WILL NOT start without the configured ports free!
11:46:55 PM [filezilla] You need to uninstall/disable/reconfigure the blocking application
11:46:55 PM [filezilla] or reconfigure FileZilla and the Control Panel to listen on a different port
11:46:55 PM [filezilla] Problem detected!
11:46:55 PM [filezilla] Port 14147 in use by ""C:\Program Files (x86)\FileZilla Server\FileZilla Server.exe""!
11:46:55 PM [filezilla] FileZilla WILL NOT start without the configured ports free!
11:46:55 PM [filezilla] You need to uninstall/disable/reconfigure the blocking application
11:46:55 PM [filezilla] or reconfigure FileZilla and the Control Panel to listen on a different port
11:46:55 PM [main] Starting Check-Timer
11:46:55 PM [main] Control Panel Ready
11:51:45 PM [main] Executing "services.msc"
11:51:57 PM [Apache] Problem detected!
11:51:57 PM [Apache] Port 80 in use by "Unable to open process" with PID 4!
11:51:57 PM [Apache] Apache WILL NOT start without the configured ports free!
11:51:57 PM [Apache] You need to uninstall/disable/reconfigure the blocking application
11:51:57 PM [Apache] or reconfigure Apache and the Control Panel to listen on a different port
11:51:57 PM [Apache] Attempting to start Apache app...
11:51:57 PM [Apache] Status change detected: running
11:52:01 PM [Apache] Status change detected: stopped
11:52:01 PM [Apache] Error: Apache shutdown unexpectedly.
11:52:01 PM [Apache] This may be due to a blocked port, missing dependencies,
11:52:01 PM [Apache] improper privileges, a crash, or a shutdown by another method.
11:52:01 PM [Apache] Press the Logs button to view error logs and check
11:52:01 PM [Apache] the Windows Event Viewer for more clues
11:52:01 PM [Apache] If you need more help, copy and post this
11:52:01 PM [Apache] entire log window on the forums

------ please help me with this error