EX4100 becomes unresponsive, loses network

I never had this issue BEFORE I upgraded to OS 5.
Now my EX4100 is hanging every few hours and only comes back after a power loss.

First CPU and RAM go up to 100% and over 300 processes are started. Then after a while, the unit is just dead except for LEDs. No connection to anything, no buttons working.
I tried hard reset (40s).
I changed the cables, the power supply and the router.
None of which worked.

Anything I can do now?