SOLVED >> Problem installing this plugin - previously installed and had issues - deleted/uninstalled and problems trying to re-install.

Thought this may be useful to others if they encounter the same problem.

Doing a fresh install and following the procedure in docs file when I uploaded 'install' files manually, last step of installation procedure, my admin crashed (cannot access it) - via trial and error I found by deleting 2 files in admin/includes/auto_loaders that my admin access returned.

deleted these 2 files;
files >> admin/includes/auto_loaders/config.usu_onetime .... and .... admin/includes/auto_loaders/config.usu

BINGO!! ..... and surprisingly (to me at least) USU works absolutely fine without those 2 files

cheers, Mike