When my program got crashed or not responding I usually end its process through Task Manager.
But, because of some cases –e.g. viruses, or registry restriction– my Task Manager cannot be accessed by pressing Ctrl + Alt + Del.
Tips:
Type in Command Prompt or Run dialog : taskkill /im processsname.ext /f and press enter.
Replace processname.ext with the name of your program, it could be be firefox.exe for Firefox, or winword.exe for Microsoft word.

When defragmenting the hard drive, make sure you turn off any screensaver you may have as this will prevent the defragmentation process from completing. You can turn off the screensaver by right-clicking on a blank area of the desktop, going down to ‘Properties’, clicking the ‘Screensaver’ tab, and choosing ‘None’ from the ‘Screensaver’ drop-down box.