So, it turns out that after two additional reboots, my start menu's pin menu obliterated itself. All my shortcuts: POOF! And, start menu search typing also didnt work properly during that period (e.g. "cmd" wouldnt find cmd.exe, etc).
Things appear to have returned to normal after the second reboot. Right-click works as expected again. I've never seen or heard of this issue before. But, this account was migrated from another system - so I'm guessing that it was something related to that, that caused the problem. Thanks for your eyes and ears. -- Espi
