Let's talk a little bit about computer registry and registry cleaners. The registry is the holding area for the computer programs in your computer. Without a computer registry your computer would not boot up to the main operating system. There are literally thousands of lines of code in the computer registry. To keep all this code in order the registry is broken up into file drawers like a file cabinet. Each drawer holds the lines of code for the programs in your computer. When the processor of the computer is calculating the code for a program the computer processor goes to the registry and pulls the code it needs to process the request. The problem arises when there is junk files in the drawers of the registry, this can cause a fast computer to run slow.
Over time the registry gets over filled with junk files or files that are left behind when you remove programs from your computer or bad links to files that lead to a dead end. When the registry gets overfilled with garbage files the computer can get very sluggish, the compute can start crashing unexpectedly, your pages start freezing up, you may start getting memory dump issues, or worse of all you start receiving the blue screen of death when you go to fire up your computer.
The problem that I run into a lot when going out to fix customer's system is that the customer ran a registry cleaner and now the computer has a tremendous amount of pop-ups or the computer runs worse now after they did a registry clean. If you plan on using a registry cleaner especially one that is free be prepared to have a windows restore disk or a windows reinstall disk handy in case something goes wrong and you are able to get back into Windows.
The old adage still is strong today as yesteryear, you get what you pay for. Free registry cleaners are for the most part bad for your computer. Most of the time the reason they are free is that somewhere imbedded in their software is numerous pop-up spam advertisements that will overtake your computer. The registry computer will scan your computer and have an advertisement pop-up that will say you have x amount of problems in your registry and if you pay x amount of money they will fix the issues. This is spam and I highly advise that you do not fall for this.
If your computer is running poorly I highly recommend that you find a reputable computer repair service in your area and contact them to do a diagnoses of your computer. Sometimes your computer will need to be formatted and the windows system will need to be reloaded in order to get the computer running like brand new again.
I hope this article answers your questions for computer registry cleaners.