a problem about the installation of wordpress

[FengFeng]

when i install the wordpress,it echo out this

Fatal error: SUHOSIN - Use of preg_replace() with /e modifier is forbidden by configuration in /home/fengfeng/public_html/wordpress/wp-includes/kses.php(627) : regexp code on line 627

i dont know why.Thank u for ur replies;)

[Corey]

Upgrade your PHP version to intermediate here: http://x10hosting.com/login

[FengFeng]

Thank you.BTW,why i must upgrade my php version??i can install wordpress before my site suspended.Although my site is unsupspended now,i cant install the wordpress.

[Corey]

The default version of PHP has been locked down for security, to use certain functions you need to upgrade.

-Corey

[FengFeng]

Thank you.
At first,i choose the "Basic PHP Configuration - Upgrade pending",but it make me tell the reason and i cant found the place to tupe the reason.
So,i choose the "Advanced PHP Configuration"....