Search buttons change position on toolbar

The two search buttons -- for (1) submitting a search and (2) toggling the drop-down list to select which space to search -- keep changing position.

Upon an initial install of OA, they display to the right of the search field, on the same line or row as the search field.

After clearing Drupal's cache, they display below the search field, creating a new line or row on the toolbar.

If I run update.php, even if there are no new updates to apply, the two search buttons return to their original position next to the search field.

As soon as I clear the cache, they move again; running update.php returns them to their proper position. See attached screenshot.

I first noticed this problem in OA 7.x-2.45 and also now in 7.x-2.50-rc1. Both Chrome and Firefox display the change and it happens for both authenticated and anonymous users.

Is this an expected behavior? If not, how should I troubleshoot and fix the problem? I can't find anything in the CSS that would be causing this.

Thanks!