Yes, it went back online shortly after I posted here.
Sara - yes,
http://divasindubai.com returns an empty page (zero bytes long), but the forum works (
Discussion Forums for Scuba Diving, Freediving in the United Arab Emirates - Powered by vBulletin), so it is not a problem of domain resolution, but rather the index.php scirpt is either broken, or the underlaying database is corrupted. If you can connect to it via FTP, verify if the index.php file is all right - reupload a backup copy. If it does not help, contact the host to look at it or to restore the website from the last backup.