In my settings, I selected the option to let everyone register. After they put their username and password and click on register, they get a blank page and they don't get the registration e-mail. But they are added as users.
You can try it here: http://www.louerunappart.ca/wp-login.php?action=register
I am using Woo Theme's Listings theme. But I deactivated it, as well as my plugins (Codestyling), and the problem remained.
I should probably say that when I was working on my website yesterday, I got an 500 Internal Server Error and could not access anything on my site (not WordPress or not front end). But I used FTP and deleted the .htaccess file. The error went away and I was then able to access WordPress and I let WordPress generate a new .htaccess file by going in the Permalinks section and clicking on Save. I'm not really sure if the registration problem started after this or if it was already there before. I just know that at some point, people could register and now they get the blank page and no e-mail is sent.
Any ideas? Thanks so much for your time!