Don't believe that has anything to do with Reaper. Google "Winsxs error" to sort it out.
But are you sure you've added the correct folders to scan for vst's in Reaper prefs? Many non-VST .dll files are found all over your hard disk and will crash Reaper when it tries to load them as plugins. Reaper should only be scanning folders you actually have installed your plugins. Looks like you have Reaper scanning your entire C: drive for plugins.
Welcome to the forums, btw.