While working on an existing Drupal site I've noticed a strange glitch that causes any PHP operator with > in it to act like a ?> tag. This is happening in in Drupal pages that I create that have a 'Input Format' of 'PHP code'.

For example this line of code
foreach($array as $key => $value){
results in a very broken page that prints out
$value){

Does any one know what could be causing this? My Dev environment is XAMPP. Drupal version is 6.15. PHP version is 5.2.9.