Magento Unable to allocate memory for pool /lib/Varien/Autoload.php on line 93 : This issue came very frequently if you are using APC in your system . so the simple fix for this problem is , to disable to APC you can do this via .htaccess file . Add the following code in your .htaccess
php_flag apc.cache_by_default Off
Enjoy , Magento coding .
