I had the issue that only the "stylesheet_dir"-part of a converted "url()"-path was displayed, not the filename or any parts put into the parantheses.

Solution was in function _filterStylesheetUri() (Plugin.class.php)

$matches wasn't associative, but rather numerical array. so, $matches['url'] etc returned nothing; replacing by $matches[2] works now.

Maybe this is actually just an issue of that hosting provider, but just for the record...

PHP Version 5.2.6-1+lenny6