Core/Loader 346 Issue

Do you have the full error from your log? If that means line 346 from system/core/Loader.php then it would reference

PHP Code:

// Load the DB class
$CI->db =& DB($params, $active_record); 


Without looking too deeply into it (and someone more knowledgeable than I can chime in), I'd hazard a guess and say your database (or connections) is getting overloaded from the traffic spikes. I can't be sure without actually seeing your system but try checking your database error logs and/or activating your database slow log to see if there are any egregiously slow queries whose effects can be exacerbated by high traffic loads. Otherwise, I'd start checking the webserver error logs for anything out of the ordinary and be on the lookout for connection errors to help lead you to a culprit. This is all just a guess and I could be way off but it wouldn't hurt to check.