Gigabyte board are just a ***** to deal with. Mine was doing that double boot thing because I had an external hard drive plugged in.
Since I've unplugged it, I haven't had any double boots. The automatic reset is just a stupid safety feature that doesn't even work properly.
A lot of people have had problems with Gigabyte boards. If it were me, I would get a new motherboard. I won't be getting a Gigabyte board for my next computer, that's for sure. I've been very unhappy with mine.