Wanted to add this question to the pool in case someone has the same problem
I was unable to update Visual Studio 2017 on Windows 7 and got the following error:
Unable to install the files to target location. Error: The folder
'c:\Program Files (x86)\Microsoft Visual Studio\Installer'or a file within it is locked by another program. Close any applications that might be using it and try again.
The initial solution I found was to reinstall Visual Studio but felt that it might be unnecessary. The solution I found was to close down Visual Studio, go to
C:\Program Files (x86)\Microsoft Visual Studio\Installer
and rename the folder "Installer" to something else, then run vs_installer.exe from the renamed folder.
Hope that helps someone.