I've got an MSI Wind, model U100 that's been running Ubuntu without trouble for a long while. After upgrading to 10.04 a few months ago, I've had this strange problem. As soon as I unplug the laptop from the power source I get the warning dialog telling me that my battery is critically low, and the laptop suspends, regardless of what the battery level actually is. If I then turn the laptop back on, it runs fine and shows the correct battery level.
I've been working around this by manually suspending before switching to battery power, but I'm wondering if anyone else knows the cause or a fix.
I think this thread talks about this issue.
There's also a bug report on Lanchpad that may apply. See comment #4.
As a kludgy work-around, I turned off auto-hybernate by putting the following command into my /etc/rc.local file.
gconftool-2 --type bool --set /apps/gnome-power-manager/general/use_time_for_policy false
On the downside, if I forget to plug in my computer it just dies after the battery is spent.