Finally getting rid of this Drupal error

After many months I finally found the time to search again for a solution regarding the "unserialize: Error at offset 446 of 23435 bytes in variable_initialize()" problem of my Drupal installation. You may have seen it every once and a while when you visit this page.

If you have a similar problem: Just install the module VariableCheck or read this post (and comment #9), thanks to the authors!