Hi,
I think that i have solved the problem.
I deleted all entries in accounting part in folder:
/var/register/system/acct/entries/
The problem was (i think), not in free space but in number of files in “entries” folder.
Zeroshell is now working fine for two days.
P.S.
You need too delete all files and folders in:
/var/register/system/cp/Connected
/var/register/system/cp/Disconnected
and
reboot Zeroshell.