apc -battery backup system

[MJmax]

I am having a problem with my computer recoginzing my battery backup system, when I first hooked it up the device manager recognized it but soon after it was gone! When I try to install the backup software the program tells me that it does not see the unit being connected to the computer?? I know that it is somewhat working because the power went out for a second one evening and it kept me running, but i cannot install the program to back me up if i were to working on something important. All of my 4 usb's on the back are full could it be overloaded?? Any help would be appreciated!!!