Download the new RouterOS 5.24 release over the torrent network: http://www.mikrotik.com/download/routeros-ALL-5.24.torrent
Otherwise please visit http://www.mikrotik.com/download to pick exact version!
5.24 changelog:
*) l2tp - fixed problem with reconnects when it added multiple ip addresses;
*) wireless - fixed AES encryption speed issues (upgrade suggested);
*) lcd - changed gamma, which gives greater contrast
*) fix reboot when running on third party hypervisors;
*) ppp client - fixed possible loss of configuration after reboot for some modems;
*) fixed wifi led order on "SXT Lite5";