I have the same problem.
Ubuntu 11.04 (problem since version 9.x) 32bit Graphics Card: Intel GMA X3100 MSI PR400-016PL laptop
The problem occurs: work on the battery, unplug the power adapter.
I reported a similar problem: https://bugs.launchpad.net/ubuntu/+bug/775088
I have the same problem.
Ubuntu 11.04 (problem since version 9.x) 32bit
Graphics Card: Intel GMA X3100
MSI PR400-016PL laptop
The problem occurs: work on the battery, unplug the power adapter.
I reported a similar problem: https:/ /bugs.launchpad .net/ubuntu/ +bug/775088