Boot Time Defrag : not responding

Hi,

I selected the Boot Time Defrag settings :

- The boot files are said defragged

- the D: is said defragged

- but no news for the rest

What are the possibilities :

- C: is defragmenting and time consuming ...

- while that process is running I cannot log on my PC : way to interrupt that process ?

Thanks for your help.

Rbmn