1.7.2 - server unexpectedly dropped the connection

[eluser]adamfairholm[/eluser]
I just upgraded to 1.7.2, and I keep getting this error on my local machine (using XAMPP):

Code:

Safari can’t open the page.
Safari can’t open the page “{local path}” because the server unexpectedly dropped the connection. This sometimes occurs when the server is busy. Wait for a few minutes, and then try again.

Using an echo and die() I traced it to line 202 in CodeIgniter.php:

Code:

$CI = new $class();

Any ideas why this would be happening? Pretty weird!