I'm running drupal 4.5 (i know it's old, but it's the latest in debian stable). If I upload the 4.6.x-1.x-dev tarball to my theme/engines directory (either as a tarball or unpacked to a folder), I can no longer log into the site. If I remove it, i can log in again.

Does this work with drupal 4.5? I tried with the file labelled HEAD & the same thing happenned.