I understood that, I've been trying to come up with something...
I don't know why only "Defrag" would do it, I wish we could simply restore the Defrag.exe file from the install disk like we used to in XP.
64 bit Windows 8?
Ok, I think I got it, you are trying to run "Defrag.exe" which is a DOS program. You need to search for
"Dfrgui.exe"
And that is the one that runs in Windows.
the other, "Defrag.exe" runs from a command prompt, so you would have to run it from there, or from the Run command. That may be why it is crashing the OS.
I'm going to do a little test... No, it didn't freeze. Try other Command Line programs.
If this is the system, then we have to start with an SFC /scannow, if that doesn't help it, a DISM restore health command.
Here is the tutorial for the DISM command.
Yah I think I see, it's not running the Dos command, it's crashing calling up the GUI. So the Component Store has to be fixed.
http://www.eightforums.com/tutorials/26512-dism-fixing-component-store-corruption-windows-8-a.html