FYI, it looks like the private messages don't work when you try to send them from the profile page.
The PM link on the profile page is always using a user id of zero. Here's the link I get every time:
However, it should have the proper user id number in the url... in my case it's 15882. So the URL should look like this:
You CAN send a PM from the Private Message link under a person's name in a discussion thread, just not from their user profile page.