Error: Apache shutdown unexpectedly. This may be due to a blocked port, missing dependencies,

This error from XAMPP is bugging me from sometime and I need to check which process is causing the problem.

Error:
Apache shutdown unexpectedly.
This may be due to a blocked port, missing dependencies,
improper privileges, a crash, or a shutdown by another method.
Press the Logs button to view error logs and check
the Windows Event Viewer for more clues
If you need more help, copy and post this
entire log window on the forums

Simplest solution I got is to use this command at command prompt:

> net stop http

It stop all programs using port 80. It gives us a chance to say Yes/No in Windows 7.

cmd.exe need to run as Administrator in Windows 7. (Start menu, search cmd and Right Click then Run as Admin.)

The above solution is discussed here.