What did you do to cause this? Go to AdminCP, create new Milestone, then delete that Milestone.
What page were you on? Milestones listing in AdminCP.
What PHP and MySQL versions do you run? dev-lang/php-5.3.13 dev-db/mysql-5.1.62-r1
Describe the defect: When you end up on page /admincp/milestones.php?delete=x, the page is blank. It should redirect you, but it doesn't work, because of a typo in the word "Location" in file /admincp/milestones.php, line 330.