Registry First Aid should be installed in/under each Operating System where registry requires checking.
Since Registry First Aid will search disks for registry corrections, it is important to select which drive (or folders) to search for corrections.
If your machine has several Windows operating systems installed and any another system "Windows" or "Program Files" folder is visible for currently booted system then there are probably many system files with the same name in different folders. Registry First Aid will find all the matched files and may insert a file correction to not currently loaded Windows installation.
In this case the user must exclude folders of other systems from the search for corrections. Please read the topics List of paths where to search for corrections and List of paths excluded from the search for corrections.
Usually we suggest excluding from the correction scan "Windows", "Program Files", "Documents and Settings" folders of other installed systems.
Not doing this may replace local system file references (such as C:\Windows\some_file.dll) with references to a parallel system (E:\WinNT\some_file.dll). Different Windows versions may have the same file name, yet different functions within each environment.