Hi,
One of the reasons why we receive such messages could be:
1 It was combination of ipv6 being enabled and automatic mail notifications enabled.
2 Message: Rapid Deployment cannot start because gateway has undergone configuration changes.
Meaning:Because RD(Rapid Deployment)requires factory-default settings,a security device(gateway)with non-default configuations cannot use RD.
Action: Reset the device to factory default settings by executing the CLI command unset all,then save,then reset.
I would suggest try to follow the 1st step and see if it helps. In order to try with the 2 option make sure that you take a config backup.
You can also refer to the following link to find some information about the same http://forums.juniper.net/t5/ScreenOS-Firewalls-NOT-SRX/Netscreen-5GT-auto-reset-problem/td-p/151480
Do let me know if the above steps helps.
Regards,
Arvinder