When I tried to defragment the disk I get the message "MMC cannot open the file C:\WINDOWS\system32\dfrg.msc. This may be because the file does not exist, is not am MMC console, or was created by a later version of MMC. This may also be because you do not have sufficient access rights to the file."1 person needs an answerI do too

Your must be logged in as admin, go to safe mode and then run defrag or use below tool to fix, click here to download How to Go in SAFE MODE ------------------------------- To go into safe mode -- Press F8 key as soon as the pc restarts. (You will have do again if pc starts in normal mode.) You would see a black screen as soon as you hit f8. On the black screen >> select the option that says Safe mode with Networking XP / Vista Now DefragTech Expert