Registry Healer does the much it can to correctly determine what registry entries are really invalid and what should not be changed. But user should always look through the list of found registry errors to verify suggested corrections. If you find an entry that has a wrong default correction you can correct it manually or add it into exclusion list. Registry Healer does not scan registry entries that are in exclusion lists.
Of course, the first program running may give you too many errors to look through the all. But you can correct only a part of them: unpick all items in the list and pick up only those entries that you have verified. Then apply corrections.
It is suggested to make only a few corrections at once. This may help to figure out a problem registry entry that should not be modified, if something will go wrong. You correct the registry by portions and you will be able to restore (if needed) the modified values by portions from separate .reg backup files.
This is the most safe way and you can follow it without paying - with the restricted version!
You can be sure that the program works on your machine - do the such partial corrections with unregistered version of Registry Healer. In this case any correction part will contain up to 10 invalid entries.
Running Registry Healer once a week in the future will decrease the number of invalid registry entries, and their correction will not be a problem.