Search OK in block but crashes if in logo area

Using Drupal 5.7. Theme is "CristalX4Drupal".

As usual, you can put a Search field in a Block and/or in the same area as the site's logo. (The former you choose in the Blocks screen; the latter you choose in the Theme's settings.)

But here's what's strange: searching works fine if initiated via the search block, but leads to a blank screen if initiated via the search field in the logo area!

Any thoughts as to why?

Thanks in advance!!