Couldn't run from cmd, directly, despite various contortions (and the fact that I am Administrator), so, this AM, as suggested elswhere and in another context, stored your command as a .bat on desktop and right clicked to get the option to run as Admin.

Bingo. No complaints and now the key has REG_EXPAND_SZ.

Reboot is again in order to test the original script again.

Post Reboot Update: :(

Looks like time to reinstall.

Update2: SOLVED! There's much useful info in this thread, which led to the conclusion that reinstalling Perl was the first best option. Using AS on Win7 (and probably elsewhere), right clicking the Perl executable in REMOVE PROGRAMS brings up 3 options, of which "Repair" uses the originally downloaded .msi.

... and, lo and behold, the quirks are gone!