Possible fix for those experiencing this problem:• Open up Command Prompt as an Administrator
(you will need Administrator privileges for the second step so, if that's broken from the start menu or power user menu, the easiest way will be to launch directly from the Command Prompt executable. Click Win+R to bring up the Run dialog and type:
"C:\WINDOWS\system32\cmd.exe"
and then CTRL+SHIFT+ENTER
• Enter
regsvr32.exe /u "%ProgramFiles%\J River\Media Center 27\JRShellExt.dll"
or replace %ProgramFiles% with the correct install path for Media Center.
You should get a dialog acknowledging successful unregistering of the shell extension. If not, something went wrong with path or permissions.
• Next, enter
regsvr32.exe "%ProgramFiles%\J River\Media Center 27\JRShellExt.dll"
You should again see a dialog pop up that confirms the shell extension is successfully registered.
To get Win+X Power User commands or the Admin Command Prompt/PowerShell functional again from the Start Menu, it may be necessary to restart Windows Explorer. This can be done right from the same open Command Prompt:
taskkill /F /IM explorer.exe & start explorer
This procedure worked for me and I have created a simple batch script to quickly and easily run fix this on other PCs that have this problem or in the future should it recur.