Critically low battery warnings even if connected to AC supply

Using a laptop here; when I'm connected to an AC supply, my battery charge is sometimes detected as going down (screenshot: http://2.bp.blogspot.com/_pA5P9BzH5uM/SglQoveE48I/AAAAAAAAAC4/vzP7A7dJc3g/s1600/powerhistory.png). That's not the main issue, and is probably caused by faulty hardware. The main issue is that Ubuntu will warn the user of an impending shutdown due to critically low battery, even though the user is plugged in. And after a while Ubuntu will actually shut down, leading to some annoyance and possibly lost work.

Using Ubuntu 9.10. (The screenshot was from last year, when I was still on Ubuntu 9.04, so this is probably a regression.)

The fix shouldn't be too hard; including a check for whether the user is plugged in should suffice.

ProblemType: Bug
Architecture: i386
Date: Sun Feb 21 11:18:04 2010
DistroRelease: Ubuntu 9.10
Package: ubuntu-desktop 1.175
ProcEnviron:
 LANG=en_SG.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-19.56-generic
SourcePackage: ubuntu-meta
Uname: Linux 2.6.31-19-generic i686