A few years ago, I moved my blog from Wordpress to Drupal. It was a rather painful experience then, theming Drupal to do what I wanted, because it was my first Drupal website and it was Drupal 5.
One day, when tidying up files and directories on the server, I mistook the blog for a test site I created earlier, and 'accidentally' deleted the entire codebase and database in that one instant. After that I was too heart broken to recreate it (I didn't use any version control or backup at that time), and to be honest, I really hated it anyway. It was all hacked together in such a fragile manner, it was full of bugs and unusable.