I worked yesterday, downloaded and ran Registry Mechanic and found 1845 "problems". Then I ran it again and it found no problems

Today, I ran it again, I haven't installed anything, just worked on a couple of spreadsheets and read the forum and it has found 19 further problems.

Now never wanting to look a gift horse in the mouth, I was wondering how it all the sudden found these additional entries?

The registry contains information and settings for all the hardware, software, users, and preferences on your PC.
Whenever a user makes changes to settings, or file associations, system policies, or installed software, the changes are reflected and stored in the registry.
Some of these entries will most probably be redundant after use.