Cpanel + LiteSpeed + Magento = Why hard to combine them together

Previously, I used Magento shared hosting (Cpanel + LiteSpeed + Magento) but due to the speed is not good to Asia (always need to wait around 6-7 seconds to show all the content in a page). Finally, I signed up a managed VPS that provided by another hosting provider.

I requested VPS support to install Cpanel + LiteSpeed and added the Magento required items in PHP and they installed accordingly.

Actually, I installed Magento many times previously by manual in Simplehelix without any problem (download Magento from official website and upload it via FTP then install it step by step).

This time in VPS I also did it same but when the page turned to the second page of installation, the page showed a warning message as below

Fatal error: Cannot override final method SimpleXMLElement::__construct() in /home/xxxxxxx/public_html/lib/Varien/Simplexml/Element.php on line 36

Contacted the VPS support but there were unable to fix it. My VPS is using PHP 5.3. Could you please let me know how to fix the problem. Many thanks.