Certain functions within joomla rely on a high/normal php memory limit. Certain web hosting companys have a very low php memory limit, around 8mb.
Having a low php memory limit can cause problems with accessing the xmap component in the backend, and using the joomfish translation in the backend.
You can check your php memory limit in joomla by going to the help menu and clicking on system info. Click on the php information tab and search for the term memory_limit
This can be increased locally without changing any server settings.
Some people suggest adding this line to the configuration.php file. However, this file is rewritten everytime the global configuration is changed and it would be wiped out. I suggest adding it to the index.php file in the root directory, and in the index.php file in the administrator folder.
Underneath the line
<?php
add this line:
ini_set('memory_limit','256M');
Changing 32 to whatever you would like to set the limit at.
This has other benefits than just helping the backend function. A high php memory limit can speed up the database connection and generally speed up your joomla websites page loading time.