Calculation of install directory

Hi, I have a problem with automatic calculation of forum (and installation) directory. My hosting handles subdomains by mod_rewrite in Apache so forum.hostname.com Unable to render embedded object: File (internally) not found. translates to /forum/ directory but you cannot use this directory directly (forum.hostname.com/forum/ or http://www.hostname.com/forum/" target="_blank are forbidden).

Your calculator does not count with this behaviour. You (in common.php) prefer PHP_SELF (=/forum/index.php) variable to REQUEST_URI (=/index.php). I believe this is wrong. PHP_SELF path should be used only in internal scripting but not in public domain (what Location header is).
So if installation directory is located in subdirectory of currently running script I'd add this directory to address bar (REQUEST_URI variable).

Same problem occurs during installation with Script path field but I wasn't able to figure out where its value is used so I am not sure if this is wrong as well.