If you are experiencing memory issues with scripts, it may be necessary to increase the memory available to the script.
If you have access to your servers php.ini file, this is relatively straightforward - simply increase the value of the memory_limit directive to 128M then restart apache. However, I'm guessing that if you're reading this post, looking for a solution to memory issues, then the last sentence probably made little sense, and chances are that you do not have access to your servers php.ini file - this is true for most shared servers.
If you do not have access, all is not lost - you can override the value in either a custom php.ini file, or via the htaccess file - the method needed depends on the following:
If PHP is compiled to run as a cgi script then you will need to use a custom php.ini, but if it is compiled to run as a module then you will need to use htaccess. (tip - you can view your servers php_info() to find out which one)...