Welcome to the forums...
Check the folder named conf and the file in that folder called advanced.php
Look for the following...

// If you get blank pages, PHP may be crashing because it doesn't have enough memory.
// The default is 8 MB (in PHP < 5.2) and 128 MB (in PHP > 5.2)
// Try uncommmenting the following line:
// ini_set( 'memory_limit', '32M' );

Delete the "//" in front of ini.set and see if that makes a difference.