computer registry cleaning

I have read and heard plenty about cleaning your computer, and especially when it comes to the registry.
There are lots of ads online stating that you should use their program to clean the registry, as long as you pay.
Well, most of those are just plain bunk, and will probably do more harm to your computer than good.
These days there is no need to pay for such programs.  There are some very good free applications that are as good as, even better than, anything you could pay for.
When I'm explaining to computer uses about cleaning the registry, I use this analogy: imagine every day when you leave for work you have to go through a maze.  Each day the maze is different, so you can't use the previous results.  So, you have to check each way in order to find your way out. So, when you computer boots, it has to check leftovers, library files, and shortcuts to see if they work. In other words, your computer is wasting time, wasting cycles. Now imagine when you enter that maze, all the dead ends, all the paths which don't work, are closed off.  Heck, you're going to find your way out in no time! Same with your computer - removing the dead ends will save your computer from having to check all that crap when it boots. Makes sense doesn't it?
My personal choice when it comes to cleaning all the crap from my computer is: CCleaner. It was formerly known as Crap Cleaner, because it cleans all the crap from a computer - dead end library files, temp files, leftovers which aren't needed anymore.  If those files are not needed then get rid of them.  I've run CCleaner on other peoples' computers and it has found in excess of 1,000 leftover garbage files!
I use CCleaner religiously on my computer.  In fact, I set CCleaner to auto-run when my computer starts.
You can find CCleaner here.
Now, the settings are a personal taste.  But at the very least, set CCleaner to remove the temp files and cookies.  These are the settings I use.
Open CCleaner. You will be at the Cleaner option, and Windows tab.
- under IE: check off every box.  If you save your passwords (why?) then uncheck Autocomplete Form History.  Personally, I don't have my computer remember any of my passwords, because this means there is a file on my computer holding my password.  Therefore, it can be found.
- under Windows Explorer: check off every box.
- under System: uncheck the last two boxes (Start Menu & Desktop), but check everything above them.
- under Advanced: check Old Prefetch Data & User Assist History
Go to Options. Under Settings select Run CCleaner when computer starts. Under Advanced check Close program when finished. Check Save All Settings to INI file.  You could have CCleaner automatically check for updates if you'd like. I prefer to check manually.
Go to the Registry option. Check off every box. Then have CCleaner Scan for Issues. When that is complete, select Fix Selected Issues. A box will popup, select Fix Issue(s). Close box.  Any changes to the registry are saved to the CCleaner folder.
You may not necessarily notice the difference in how your computer runs, but your computer will thank you for not having to check all that crap when it boots.  Remember, be kind to your computer and your computer will be kind to you :)