I was facing the same issue and find out that problem was Autocad. Coincidently Autocad scripts use .scr as extension and it changes the default application. Then I´ve restored scr to default and installed the Xibo.scr as per documentation (instead of copying it to system32 folder) and it worked.
I deassociated the scr file extension with AutoCad by going to my registry editor > HKEY_CLASSES_ROOT > .scr and changing its Data from ‘AutoCadFile’ to ‘scrfile’.