Dell N1548P stops forwarding traffic

Have an odd situation that happens randomly once every couple months.   I have a Dell N1548P Switch that stops forwarding traffic. When it stops forwarding traffic I can not ssh to it,  on it's management IP address, and cannot ping the switch.

When I log into the console of the switch I don't see anything out of the ordinary (Maybe I'm just not looking at the right things).  Rebooting the switch either by power cycling it, or from the console resolves the issue.  After the reload I can ping the switch again,and have no trouble accessing it over the network.   all Computers are able to re-authenticate (802.1x) and function again.

System Model ID................... N1548P
Image File........................ N1500v6.5.1.3

The only messages on the console when the switch quit forwarding were standard messages to indicate MAB  (Mac Auth Bypass) timeout for some clients.

DOT1X[dot1xTimerTask]: dot1x_control.c(1446) 477 %% WARN MAB timer (90) seconds expired for client 01:23:45:67:89:AB on port Gi1/0/7

When the switch stops forwarding traffic what can I look at to determine what is happening, and what is causing this ?