Just to be on the safe side go to My Computer, right click properties > advanced > start up and recovery > settings and uncheck time to display Os's. DON'T !!!! change the default OS. And say ok ok. This should solve your problem. You can also go to your ms config and boot.ini and delete the boot line for the old OS listing. But since both are same OS you dont need to confuse and risk yourself. Just uncheck the box. Should do the trick.