Need help interpreting this server error and PHP and lead on how to fix

A friend of mine got one of those nasty server errors last night stating

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator to inform of the time the error occurred and of anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

The server log states

Feb 13 18:48:11 plesk-01 suhosin[11843]: ALERT – script tried to increase memory_limit to 268435456 bytes which is above the allowed value (attacker ‘68.253.230.80’, file ‘/var/www/vhosts/ysnews.com/httpdocs/wp-admin/admin.php’, line 109)
Feb 13 18:48:14 plesk-01 suhosin[11843]: ALERT – script tried to increase memory_limit to 268435456 bytes which is above the allowed value (attacker ‘68.253.230.80’, file ‘/var/www/vhosts/ysnews.com/httpdocs/wp-admin/admin.php’, line 109)
Feb 13 18:48:21 plesk-01 pop3d: Connection, ip=[::ffff:64.179.101.154]

Below are lines 108 and 109 of the the admin.php file of WordPress 3.51 site

if ( current_user_can( 'manage_options' ) )
@ini_set( 'memory_limit', apply_filters( 'admin_memory_limit', WP_MAX_MEMORY_LIMIT ) );

I’m trying to figure out what this pertains to?

The site was also recently updated to WP 3.51 from 3.1. I noticed that the memory limit on that setting is different and is listed below for WordPress version 3.1

if ( current_user_can( 'manage_options' ) )
@ini_set( 'memory_limit', apply_filters( 'admin_memory_limit', '256M' ) );

To clutter things more, this site was recently moved to a new Plesk server but both servers have 128mb of memory.

I am wondering if I should change the WP 3.51 setting back to 256M since this problem didn’t occur before that line of code changed.

Is this setting for the memory usage in the admin panel/media uploader…eg…size of picture able to use? Most of this is a little greek to me.

Any help is appreciated

Thanks,
Bryan