A key in the $GLOBALS array contains what appears to be the result of serializing an array.  I have fixed the problem in the code with a regexp, but I don't think it's supposed to be there.

Code to show this:
$global_keys = array_keys($GLOBALS);
foreach ($global_keys as $key)
{
  echo $key . ' - ' . $GLOBALS[$key] . '<br>';
}

On a very simple page this results in nothing but the expected variables. However, on a large and complex page I get this among the results:
;s:6:"weight";d:0;};s:6:"weight";d:0;}language - 

I'm going to take a wild stab that it's adding the result of serialization of some variable into the array keys with no value rather than adding the key and the serialized value.

The same function worked flawlessly without the regexp in PHP 4.3.1 with the exact same configuration.