I have a friend that installed an APC J type Power Conditioner & Battery Back-up on her entertainment system a few months back. She's on a rural electrical system and was having power surges and wanted to protect her equipment. She e-mailed me yesterday to say that her TV and satellite receiver was turning off and rebooting and wondered if the battery was out. APC says these should last 3 - 6 years before needing replacement. Even if the battery is bad wouldn't power still flow through the outlets to the equipment? Nothing else in the house is turning off like this and she said there's a floor lamp in the same wall outlet that the power conditioner is plugged into.
I've checked out the APC support site and there's no discussion I could find on a unit failing like this.