How old was the previous version? It is better you uninstall it first and then install the new one. The installation program for Windows offers a choice to uninstall the old version.You are little late installing 1.2.6. Now I will leak a highly classified secret piece of information. Next 1.4 version will be branched this weekend. RC1 may be built already 2 weeks from that, meaning at 24. or 25.1.2015.Release happens about 2 months from that, maybe already in March.