Suddenly I've lost the ability to access the main page of my blog. (http://www.slaw.ca) I can get in to the admin side, I can go to any page for which I know the URL except the main page. When I try to access the main page I get a 500 error saying there's been a hiccup on the server.
Of course, I'm in contact with the hosting company but thus far they've not been able to figure out the problem and I'm waiting for... the admins, I guess.
The sudden loss of access to the front page makes no sense. I've not changed anything in the templates and all the posts and comments are kosher. The error log says, though, that the call to the header in the index file is a call to an undefined function.
Can anyone suggest what might have happened?