This problem could be due to the battery pack not being installed properly.

To solve this problem, turn off your VAIO computer, remove the battery pack, and then reinstall it. To install or remove the battery pack, see Installing the Battery Pack or Removing the Battery Pack.

If the problem persists, it is likely that the installed battery pack is not compatible with your VAIO computer or has failed. Turn off the computer, remove the battery pack, and then replace it with a new one specified by Sony.