Battery Status doesn't work properly

[BTaylor]

Hi,

 

I'm running 10.5.8 on an acer aspire one. Everything works (QE, Full resolution, sound, wifi, etc.) except battery information. It sort of works in that when I plug it in, it recognises that it's plugged in and shows the charging icon, but when I unplug it, it says that "Battery is not charging" and says it's running from the power adaptor, despite showing the draining battery icon. I've attached an image.

 

Any ideas?