Burgular alarm system rings at 1:am and some times 1:30 am for the last several nights the system always flashes zone 3 for windows and the windows check out OK. It will occasionally ring during the daylight hours, any idea what's causing this problem?

Is it a wired or wireless system.

Any new eletronics or changes in home

Do you have any Teenage Kids?
How many windows? Resessed or Surface Contacts.
Could be as simple as loos wire on terminals, if hardwired.

My system started to do this intermittently, after a power black out. I turned the power off at the board and waited for a few minutes and then turned it back on, it seems to have reset itself.

What System do you have? If it does it again, take of note what zone caused the trip.