If Scandisk does not start up after a bad shutdown, make sure that the setting is enabled using the following steps:
1) Click [Start] -> [Run].
2) Type "msconfig" in the box of [Open], and click [OK]. System Configuration Utility] appears.
3) Click the [General] tab and the [Advanced] button. [Advanced Troubleshooting Settings] appears.
4) Remove the check from the [Disable Scandisk after bad shutdown] box.