If the problem Appear In Disk message "Operating system not found".

Cause:

By the time the CPU is turned on and then did post after it appeared the message "Operating system not found".

solution:

There is the possibility of corrupted operating system, can be overcome by re-install, or if you use Windows 2000/XP OS there Repairnya facilities. or there is also the possibility of your hard drive is not detected and retune.