NSA320S 100% CPU Usage

Hello
I'm using this NAS, but it's constantly at 100% CPU usage. Sometimes I can't even access the web portal and my folders, probably because it doesn't have resources to load them. I can ping it, but I can't access anything.
Rebooting doesn't help. It goes back to 100% after a couple of minutes. I use it only as a ftp and a windows share. 
I tried to disable some of the features I don't use, like Twonky Media Server, iTunes Server, Download Service, Web Publishing, Dropbox, Time Machine, Auto Upload, but that doesn't fix it.

I have two 500gb disks in Raid1. They have 16gb free space and are healthy.
Firmware version is V4.75(AANV.2)

When I press on cpu info I see this:

No. 1	python	97.1
No. 2	zyshd	2.9
No. 3	ksoftirqd/0	0.0
No. 4	events/0	0.0
No. 5	khelper	0.0
No. 6	async/mgr	0.0
No. 7	kblockd/0	0.0
No. 8	khubd	0.0
No. 9	kmmcd	0.0
No. 10	crypto	0.0