problem while starting apache

[ahsanigis15]

after installation when i started application for first time then this message was shown for apache....
12:42:14 PM [Apache] Problem detected!
12:42:14 PM [Apache] Port 80 in use by "system"!
12:42:14 PM [Apache] Apache WILL NOT start without the configured ports free!
12:42:14 PM [Apache] You need to uninstall/disable/reconfigure the blocking application
12:42:14 PM [Apache] or reconfigure Apache to listen on a different port
but when i attempted to start apache from XAMPP... it was not started and following error was shown....
12:42:20 PM [Apache] Error: Apache shutdown unexpectedly.
12:42:20 PM [Apache] This may be due to a blocked port, missing dependencies,
12:42:20 PM [Apache] improper privileges, a crash, or a shutdown by another method.
12:42:20 PM [Apache] Check the "/xampp/apache/logs/error.log" file
12:42:20 PM [Apache] and the Windows Event Viewer for more clues

please help me in this context... i am totally immature at this stage to figure out the problem...

[Altrea]

viewtopic.php?f=16&t=55579