Thread: Clocking off

I have two problems that may be connected. First, every time my computer starts a window appears saying my AVG anti-virus licence has expired. I also find that the date and time settings have changed to a date in 2006. When I correct the latter it cancels the AVG warning and aU is well. The problem returns next time I start up.

Second, when starting the computer, it pauses before Windows launches giving me a screen oftext options, one line of which says 'CMOS battery is low' and the next 'CMOS time and date are not set'. The operating system is Windows XP Home and the PC is anAcer Aspire E560-ME7L.

You're right, they are connected. The warnings and information that appear when you start the computer are not particularly helpful- they contain lots of jargon that's comprehensible only to technical people. But in this case the warning that appeared is one of the less obscure ones - the battery inside your computer has a problem.

You may be surprised to hear that all computers have a battery inside. This isn't the same as the one that powers a notebook computer; in fact, it doesn't power the computer at all in normal use. What it's used for is storing a lot of settings while the computer is switched off. This includes the configuration of the hard disks and graphics card, as well as the time and date. That way, even when the computer is switched off it can keep its internal clock going so that, next time you switch it on, the time is correct. In this case, it sounds like the battery is not just low, it's completely empty.

It's easy to replace, and should be cheap. The battery in question is attached to the motherboard - the main circuit board inside the computer. It's a flat watch-type battery, about an inch in diameter. Just pop it out and replace it with one ofthe same model (the model number should be etched on the top - it ought to be something like CR2032 or CR2025), which is available from pharmacists and hardware shops. The Acer Aspire you have is a desktop computer, so it should be easy to open the case and replace the battery. Notebook owners with the same problem may be better off getting the battery .replaced by a qualified technician because it's much harder to get inside a notebook. The same applies if you are not comfortable opening your PC, although this will obviously cost you more.