Thanks for you answer Gokul.
Here's the output of 'get log sys save' and 'get log sys' when it works normally:
ssg5-serial-> get log sys save
6.3.0r13.0
ssg5-serial->
--------------------------------------------------------------------------------------------------------------------
ssg5-serial-> get log sys
## 2016-04-05 13:13:43 : sys up(tid=80,pid=32748) exited with code = 0
## 2016-04-05 13:13:43 : nsrd-startup(tid=53,pid=32721) exited with code = 0
## 2016-04-05 13:13:47 : module_test(tid=67,pid=32735) exited with code = 0
ssg5-serial->
When it "rages" there is no way to get to the console in order to type any commands.
Kind Regards,
Marcin