Shuttle SN25 Problems: Battery?

[Housey]

I built my mum an SN25 system a few years back but of late it has been playing up, rebooting, forgetting settings etc. Now she is not a big user and when it does reboot it usually comes back to the BIOS with reset date/time so I am assuming it's probably the battery?

Couple of questions though. Could it be something else and where can I get a battery from for one of these?

Thanks in advance
Housey

 

[Guardsmon]

The battery is most likely a standard CR2032 - can be got from any electrical shop/supermarket for about £1.
Might be something more related to power though if its turning itself off.