Regmon

When using your computer to perform any task, there is a lot of activity that goes on beyond the operating system interface. If you want to get a better understanding regarding which programs access certain Windows registry keys, you can use Regmon.

Information available and enable event capture

This registry monitoring application displays not only which utilities access the registry, but also the keys they have modified - this is especially useful to users who have advanced PC knowledge and can identify suspicious behavior, thus detecting malicious apps which might have infiltrated their computer.
In addition to exploring the behavior of any running application, you can toggle registry monitoring on and off with a single mouse click, as well as disable event capturing or export the contents of the list view to an ASCII file (that you can later send to a more tech-savvy friend for analysis).

Look for a certain key and use a color-coded system

You can also use Regmon to search for a certain registry key, even if you do not exactly how it is called as you can rely on customizable wildcards and case-insensitive filters. Depending on the keywords you input, the application displays the results that best match your criteria so you might need to perform several searches until you find what you are looking for. Moreover, you can customize the utility to highlight specific records with colors you choose.

A last assessment

The only and major downside of this application is that the project has been discontinued for several years now, and that users who run newer editions of Windows will get more accurate results using the components of Sysinternals Suite.
As a matter of fact, the functionality of Regmon was integrated into another app called Process Explorer, which has gradually become a popular tool among those looking for a task manager with registry monitoring functions.