CPU Overload and high ping while doing nothing

Hi everyone,
I'm having issues with my ZyXEL NAS 326. Opening documents was suddenly became so slow that I wanted to check ping and discovered it was about 600ms and around values.
Had a look at admin panel and found CPU usage at 100%. 
So I rebooted the NAS but it was again at 100%.
There was "python" on the top of CPU tasks list... 
After many reboots and a brutal switch off from ACpower (it was no more responding) CPU is back to 10-15% usage.

What was happened? How do I know it won't happen again?

I have never had issues like that with QNap.

Thanks again,
Francesco


#NAS_Sep_2019