[A repeat of what I've posted before...]
A guide for the average computer user for NOT using a registry cleaner follows -
1.Windows is a closed source system, developers of registry cleaners are not working on definitive information, but rather empirical knowledge. Automatic cleaners will usually have to do some guesswork.
2. Modifying registry keys incorrectly can cause Windows instability, or make Windows unbootable.
3. No registry cleaner is completely safe and the potential is ever present to cause more problems than they claim to fix.
THEREFORE
4. If you do not have knowledge of the registry, then you would probably be better off leaving it alone, and definitely not placing blind trust in a program to do the job for you.