What Is Regedit As In Failed To Update System Registry?

It is a program used by the registry that allows you to manipulate (as in regEDIT) many of the different aspects of the registry itself.  In many ways, the registry is much like the genes and chromosomes that provide the genetic makeup (or blueprint) used by living things to create the vast diversity among these living creatures.  

The message you received says that your program was unable to be installed because regedit failed to update (i.e., manipulate/edit) the system registry.