httpd.exe disappeared. (Xampp 5.6.12 on Win server 2012)

[a2arakawa]

Xampp apache on windows server 2012.

Once a day* our apache (httpd.exe) stopped.
No Error log and No high workload.

We start apache from Xampp console, But after several hour httpd.exe process disappeared.
( We checked windows task manager )

Is this the bug ?

Regards
a2arakawa