Reinstall boot manager

Say FreeBSD forgets that you have Windows (boo hiss) installed on hard drive, and yet you want to continue to dual boot. Here's some easy steps to either get BootMgr running again, or to start it running for the first time:

1) Do as root "sysctl kern.geom.debugflags=16"
2) Start sysinstall
3) Go Configure->FDISK-> "OK" -> Q
4) It will ask if you wish boot manager
5) Select BootMgr