Could be conflict with some other installed program.am using XP and i have re-install n up the patch too but still kick out once i click a pic for RAW development
But Master is buggy as was it previous version.
Now just to share a recent observation.
When you right click a RAW file and select open registered application, whatever software you have registered as your registered application should run and open your RAW file.
My registered application is Photoshop, and it does not run when I right click in the Browse mode. Instead it do a RAW development behind the scene and generate a TIFF file which is then passed to Photoshop. But when I am in Edit mode, ACR will open as expected. I do not know if this is the intended behaviour or is it a bug, but I think it is the former.