The loop may appear because you have improperly configured some of the URL settings or similar. Make sure you have specified URL beginning with 'www' or non-www, depends on what kind of domain you are using. They are very different things.
You may check misconfiguration theory modifying bb_func_vthread.php file, before the code which says
if($requestUrl!=$origUrl and !defined('NO_RELOC')){
paste the lines:
echo "{$origUrl} -- {$requestUrl}";
exit;
this should give output on the screen of two addresses. If they are not equal, the loop will happen. Achieve that they both look identical.