As noticed by trevor and stephen their setup running latest CVS, Dragonfly crashes on Apache 2.0.52 + PHP 4.3.10 on Windows XP SP2.
This is caused by a bug inside PHP with the get_current_user() function.
The developers marked the bug as fixed for PHP 4.3.10 but apperently it still crashes your Apache.
We've reported the bug at bugs.php.net and commited a workaround in the CVS for this issue.
Server specs (Server OS / Apache / MySQL / PHP / DragonflyCMS):
Fedora 25 / Apache 2.4.27 / MariaDB 10.1.26 / PHP 7.1.10 / Mercurial