"The Disk Defragmenter is not installed on your computer"

Improve performance by defragmenting your hard disk

Fragmentation makes your hard disk do extra work that can slow down your computer. Removable storage devices such as USB flash drives can also become fragmented. Disk Defragmenter rearranges fragmented data so your disks and drives can work more efficiently. Disk Defragmenter runs on a schedule, but you can also analyze and defragment your disks and drives manually. To do this, follow these steps:

1. Click to open Disk Defragmenter.
   

2. Under Current status, select the disk you want to defragment.
   

3. To determine if the disk needs to be defragmented or not, click Analyze disk. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
   

   Once Windows is finished analyzing the disk, you can check the percentage of fragmentation on the disk in the Last Run column. If the number is above 10%, you should defragment the disk.
   

4. Click Defragment disk. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
   

Disk Defragmenter might take from several minutes to a few hours to finish, depending on the size and degree of fragmentation of your hard disk. You can still use your computer during the defragmentation process.
Notes

• If the disk is already in exclusive use by another program, or if the disk is formatted using a file system other than NTFS file system, FAT, or FAT32, it can't be defragmented.
  

• Network locations can't be defragmented.
  

• If a disk that you're expecting to see under Current status is not showing up there, it might be because it contains an error. You should try to repair the disk first, then return to Disk Defragmenter to try again. See Check your hard disk for errors for more information.
  

  
  

  also "hibernate" the computer instead of "shut down"
  

Many factors may cause your Windows 7 running slow: lack of memory, useless programs, wrong startup settings, junk files, registry redundancies, viruses or spyware and more.
If you computer is running slow or starting up slow, you may visit this article to learn more.

Slower Startup / shut Down / Restart Speeds are usually due to a highly fragmented hard drive.

Run the disk defragmenter by going to start >>programs>> accessories >> system tools >> disk defragmenter

It may take a very long time depending on the size of your disks and the degree of fragmentation

Alternatively , consider using a paid software solution such as Tuneup Utilities which contains a better defragmenter that does the job quicker.

When the defrags done (may take overnight) , you should notice an increase in speed when starting up , shutting down , restarting , hibernating , launching programs and in Windows Explorer ie. My Documents , my computer etc

Hope this helps