During install of SONAR X3 Pro, it gets to hold where it says it can not overwrite mscrv71.dll in the Windows\system directory.  A search of that directory shows no sign of mscrv71 but does list mscrv100.  Anyway, I ignore the request so it will go away.  SONAR X3 completes install and appears to run just fine.  So, where is the mscrv71.dll, why won't it overwrite, and what impact will the old file have on SONAR X3 performance?
 
Thanks!!!

Not an answer but did you run the install with the "Run as Administrator" option.  This seems to be the workaround for these type of install associated niggles.

If you are not showing system files you may not see those in Windows.
Make sure that you do a clean boot and stop all background apps before installing SONAR. One of your apps probably have that file in use preventing one of the redistributable installers from working properly.