Forum "Installer not compatible with PHP 4"
 

When I go to http://www.myforum.com/install/install.php I get this error:
Code:
Installer not compatible with PHP 4
The problem is, that I have PHP 5 enabled on my site. I even double-checked a few seconds ago, and yes, it is php 5.x

upgrade.php says the same thing. Could someone please help me finding out what the problem is?