Regestry checker is actually a misspelling of the word registry checker. Even at that a registry checker is better known these days as a registry cleaner. Back in the days registry checkers were around they were used to findproblems in the Windows operating systems registries. The checker would print to the screen a list of the problems it found and then leave the computer user to figure out how to fix these problems.
A registry cleaner will locate all the problems with a Windows operating system’s registry as well, the difference is it will repair all the problems with the registry. As you can see, a registry cleaner is a big upgrade from a registry checker.
The reason anyone would be interested in getting the corruption cleaned out of their registry is because this corruption can cause a PC to act up any of several ways. Most notably registry corruption will cause a computer to lose all or a significant part of its speed. Potentially a computer will slow down so much because of registry corruption it will be unusable. More commonly however, the PC will slow down just enough to be aggravating.
Aside from that registry corruption can possibly cause computer errors, freezes and crashes. This includes blue screen crashes. So, the bottom line is a computer should checked for and cleaned of registry corruption periodically so all these problems can stopped before they make a computer become a big problem for anyone who uses it.