The support for PHP 5.2 ended in August 2011, so I recommend to update the PHP installation.
The configuration site on magentocommerce.com shows that PHP 5.3 is required.

Some weeks ago we had some issues with a PHP 5.4 installation, EE 1.12 and atomic repo (some segmentation faults) and we stepped back to 5.3.

Update: The error was


  Fatal error: Cannot override final method
  Mage_Core_Model_Abstract::clearInstance() in various PHP-Files


with PHP 5.4.17

Potential PHP problems with EE 1.13 or CE 1.8
Sometimes I leave a comment like "Stack Overflow is not your personal research assistant," but am accused of being rude.  How can I craft a comment that is seen as civil to the community and instructive to the OP?


What tone should I strike in comments?
What are some examples of bad comments and their better replacements?

