i have a particular problem with my UPS. it is a 500 VA one and i use my system with a 15" crt colour monitor on it. i have two hard disks (one-40 gb, other- 8 gb) and two cd drives as mentioned. The main problem is that my system often hangs when a power failure occurs even when it is connected through the UPS. the earthing was good. why is this happening? it should atleast restart if at all there is a lag in the switching to the battery. but why does the system hang? this problem is irritating me too much as we have frequent power cuts in our area and its embarrassing to switch off the ups directly while my work is still going on. My UPS is also recently not giving the required standby time. on the battery, the system works in an idle condition for just 2 minutes and a half. should i change the battery?