I think there's a problem when, in install_forumjump_depth.php, this line gets executed:
PHP Code:
$result = mysql_query ("UPDATE template SET template = template + '\$forumjumpdepth = \"$forumhomedepth_value\";\n' WHERE title = 'options'");
The field 'options' in table 'template' ends up being a simple 0, so all the previous options get deleted, and that's why I used to get the eval()'d errors.
Hope I helped.