he easiest and safest way to do this is:
* Go to Start > Programs > Accessories > System Tools and click "System Restore".
* Choose the radio button marked "Create a Restore Point" on the first screen then click "Next". Give the R.P. a name then click "Create". The new point will be stamped with the current date and time. Keep a log of this so you can find it easily should you need to use System Restore.
* Then go to Start > Run and type: Cleanmgr
* Click "OK".
* Click the "More Options" Tab.
* Click "Clean Up" in the System Restore section to remove all previous restore points except the newly created one.
Download install and update Ccleaner
After installing and updating go to options - advanced and tick prompt for registry back ups
Now Start up in safe mode
Do two runs
1) Click on problems and tick all. Click on analyse. At the end you will be prompted for storing a backup.
This will be stored, as a default, in My documents.
2) Click on cleaner click on analyse and accept all files to be removed.