i just recently brought home my mac pro that i used for work. i have it connected to the the apc i was using my macbook pro with. the model is an APC BACK UP UPS 350. for some reason it keeps shutting the machine down and the ups beeps its tone and doesn't even have time to back up? what should i do? is it my apartment building's power to blame? is it this UPS? any recommendations on another UPS or surge protection?