Moodle server was down from mysql error

I came into work today, Monday and had a noticiation from a customer that our moodle site was down.  Her moodle site anyway.  I checked and verified what she reported.  The site was displaying a database error message.

I checked another of the moodle instances that runes on the moodle server and it also was displaying the error.  That told me the issue was on the server and not in the specific moodle instance.

I remoted into the server and restarted the wamp services, including the wampmysqld service.  It did not restart.

The next lowest piece of hanging fruit was to recycle the server.  Which I did and the site sprang back up.  Good.  Blood pressure starting to abate. 

With BP lowering and the brain able to think more clearly, I thought to check the server error log to see what the issue with mysql was.

This is the error reported in the logs.  Interesting from 1st to the the failing message

This was first Default exception handler: Incorrect sesskey submitted, form not accepted! (about 300 times)

Then this   Default exception handler: Invalid user Debug: SELECT id FROM {user} WHERE id = ? AND deleted = ?\n[array (\n  0 => '2867',\n  1 => 0,\n)]\r\nError code: invaliduser\n* line 1403 of \\lib\\dml\\moodle_database.php

Then the failing error message PHP Warning:  mysqli::mysqli(): (HY000/2002): An operation on a socket could not be performed because the system lacked sufficient buffer space or because a queue was full.\r\n in C:\\wamp\\www\\gvboces\\lib\\dml\\mysqli_native_moodle_database.php on line 375 (about 300 times)

This looks a little suspicous to me.  Could be nothing, but could be a hack or virus attach of some sort that caused the sql service to shut down.  Restarting the services did not correct, rebooting the server did correct.

The end.