We have a SA540, who need a restart every 12-24 hours (power off/on). The hardware lock, and it is not possible to connect via GUI or ping the hardware.
The hardware have been change, but the problem still appears.
There are only 10 local user and 7 IPSEC VPN users.
Are there a firmware bug
There is a firmware release on the Cisco website. While it does not affect the issue that you are experiencing, it would not hurt to apply the latest firmware and then factory reset your device. Should you continue to have the same issue, you may need to call 866.606.1866 for further support.