I have a computer in my "office" (a 5'x10' storage room) at the commercial building that I own. This computer serves one purpose only, that being as storage for the four security cameras that I have monitoring the building. The computer is hooked up to a UPS so that, in theory it should never lose power.... but it is (losing power). It will consistantly shut down and reboot for no apparent reason. I may be able to get by for a week or two or I may get by for only a matter of minutes. The computer reboots, but never totally restarts so anything from the cameras after the reboot is lost. I have gone through two UPS units, replacing the first one thinking it was the problem. The second one (another brand) appears to be no better at resolving this problem. I am suspicious of the power supply, but don't want to rip into it before taking other suggestions. Any ideas on what could be causing this? The OS is Windows XP. The computer is a Compaq from about 3 -4 years ago.