I think this is an issue with /wp-admin/edit.php and possibly firefox. While I'm logged in as admin and I delete a post from the manage tab, it looks like it has been deleted, but if I refresh the page, I get a popup asking me "Are you sure you want to navigate away from this page?" and upon clicking yes, the page refreshes and the post is gone.
If I hit the edit button instead of the delete button, and then use the delete button on the edit page(so I'm at
/wp-admin/post.php?action=edit instead of
/wp-admin/edit.php), the post gets deleted.
I'm running WP-cache, but the behavior persists even if the plugin is disabled and the cache is deleted. I've also tried logging out, deleting my browser cache and cookies, and logging back in, and disabling greasemonkey, which isn't running any scripts on that page anyways.