Actually, it has nothing to do with the threaded mode; this issue is in the flat mode wink . After playing a little more with the templates, I saw that this could be easily fixed by changing the following line in Showflat.tpl:

Code
<a href="{$config.BASE_URL}/ubbthreads.php{$var_start}ubb{$var_eq}showflat{$var_sep}Number{$var_eq}{$postrow[post].Number}#Post{$postrow[post].Number}"><img border="0" src="{$config.BASE_URL}/images/{$style_array.icons}/{$postrow[post].Icon}" {$images.icons} alt="" /></a>

to:

Code
<a href="#Post{$postrow[post].Number}"><img border="0" src="{$config.BASE_URL}/images/{$style_array.icons}/{$postrow[post].Icon}" {$images.icons} alt="" /></a>