Remove invalid registry entries:

Next up is the registry. Frankly, the registry is overrated as a speed tweak, in general, but it does get large and can contain many invalid references. The registry is not an area for even the average computer user to be playing around in. The good news is CCleaner has a safe registry cleaner built in, so why not clean out old, invalid entries?

Click the issues button.
Click scan for issues.
Click fix selected issues.
Just to be safe, ensure you back up the reg at the prompt, although i have used this feature thousands of times and never had an issue!

Thats it, your done, a safe, fast registry clean.