I had a Dell that did that once or twice. If you unplug the power, remove the battery, wait a minute, put the battery back in, and re-start...it should do the trick.
Not always good to hard-shutdown/reboot a system...but sometimes it needs to be done. Doing this is no different them unplugging a desktop. Cutting all power and rebooting to see if Windows reports any errors.
You can always run CHKDSK after the reboot to check the disk integrity as well.