O.k. Found another site running vBMediaWiki and this way also the point, breaking the template navbar on my site: vBMediaWiki leads the vB-variable $relpath to "wiki/Article" instead of "../wiki/Article", so {vb:raw relpath} cannot be used in the navbar for wiki pages.
This happens in the function fetch_relpath (class_core.php), since $basepath ist not the forum-base any more, but the wiki-base...
Workaround: Use
Code:
<vb:if condition="THIS_SCRIPT == 'mediawiki'">/</vb:if>{vb:raw relpath}
(on your site perhaps
../ or even something else).
Bruno