Hey all, My dad's desktop just started displaying a really odd error -- it gives a battery warning that laptops usually give when the battery is low. It says: "CRITICAL BATTERY You should change your battery or switch to outlet power immediately to keep from losing your work" The machine was originally a HP Pavilion a1340n, but the motherboard was changed after a power surge, so it no longer has all factory hardware. I'm hoping this issue doesn't require a reformat, since this computer won't install Windows without detecting the original motherboard, so the last reformat took me a long time to figure out. It is currently running Windows XP Professional that is fully updated. Does anyone have any ideas why a desktop computer would be displaying a low battery error? The unit is connected to a APC UPS, but that unit is not showing any error lights. I tried searching google, but the first few pages of results only showed people with similar problems, but no resolutions. Any ideas? I was thinking of buying a new CMOS battery and then testing the old one to see if that could be bad. The only things I can think of are a failing power supply, bad CMOS battery, or faulty UPS unit. Is there a way to test the power supply or UPS (besides its own diagnostics)? Thanks for the help -- I'm hoping someone here has seen this before.