PHP 5.0.3 Variable Bug or Something More?

I've ran across some strangeness which I can't figure out. When I run
the following code I get a Seg Fault / Bus Error in my apache log
(SegFault on Linux and Bus Error on Mac OS X).

	$rate_id = Core_Request::get('rate_id','integer',true);
	$plan_id = Core_Request::get('plan_id','integer',true);
	$min_seats = Core_Request::get('min_seats','integer',true);
	$max_seats = Core_Request::get('max_seats','integer',true);
	$rate = Core_Request::get('rate','float',true);
	$DB = Core_DB::getInstance();
	
	$query  = "update subscription_prices set ";
	$query .= "min_seats = $min_seats , ";
	$query .= "max_seats = $max_seats , ";
	$query .= "rate = $rate ";
	$query .= "where plan_id = $plan_id ";
	$query .= "and rate_id = $rate_id ";
	
	$DB->query($query);
	$DB->commit();

When I change the variable from $max_seats to $_max the error goes
away. Also it appears that the $DB->query(); and $DB->commit(); calls
are being executed and the session is being written to the database.
I've also had this happen on the following:

	$flat_rate = Core_Request::get('flat_rate','float',true);
	$flat_seats = Core_Request::get('flat_seats','integer',true);
	$plan_id = Core_Request::get('plan_id','integer',true);

	$DB = Core_DB::getInstance();
	
	$query  = "update subscription_plans set ";
	$query .= "flat_seats = $flat_seats , ";
	$query .= "flat_rate = $flat_rate ";
	$query .= "where plan_id = $plan_id ";

	$DB->query($query);
	$DB->commit();

To fix this I ended up changing the name of the variables from
$flat_seats and $flat_rate to $seats and $rates to get the bus error to
disappear. I've tested this on Mac OS X Client 10.3.7 running Apache
1.3.33 and PHP 5.0.3 as well as Debian Linux with the same set up. Here
is the output from "ktrace httpd -X" with the crash at the bottom.

http://www.fwi-archive.com/~chris/debug.txt

Let me know if you need any more information.

Chris Cowan