You may need to increase php memory, create a file called php.ini in your root folder and add memory_limit = 128M you can increase it, but the hosting provider may limit it.
This will assign more php memory and you can check if it has increased by creating another file called phpinfo.php and adding <?php phpinfo(); ?> to the file, save it and run the file by typing your domain/phpinfo.php
Delete it after as it is a security issue, all the information about your php server setup is in there.
It might take 5 - 10 min for the change to be seen on the memory limit but just keep refreshing and scroll down to where it says memory limit.
Control F5 to correct refresh.
Hope this helps. If not send me an email via my site.
and ill help you out.