The recording is almost certainly not failing. Your TV is switching the box off with it.
Most TVs send a standby command down the HDMI cable when you power them off, and everything connected obeys, your BuzzTV included. The feature is HDMI-CEC, but every brand renames it: Sony BRAVIA Sync, Samsung Anynet+, LG SIMPLINK, Panasonic VIERA Link, Philips EasyLink, Sharp Aquos Link. Others just call it HDMI Control.
Turn it off on the TV. Search the TV settings for CEC, HDMI Control or the brand name above. On Sony it is under External inputs, on Samsung under External Device Manager, on LG under General. Switching it off does not affect picture or sound.
To check: start a recording, turn the TV off for five minutes, turn it back on. If the box is still recording, that was the cause.
Two other things cut recordings short: changing channel during a recording, depending on your provider, and slow storage. Check Main menu > PVR > PVR options to see which drive is selected. USB memory sticks are not recommended.
Still stuck? Email cs@buzztv.com with a photo of the white label on the underside of your device, which we use for utility and system checks, and tell us what you see on screen. Support is Monday to Friday, 10:00 to 18:00 Eastern.