I'll be damned! Not only did you nail it again, but I was so blinded by context the first time I checked this that I didn't see the obvious problem until now.
> set | find "ake"
Make=LENOVO
A bug that only exists on ThinkPads! No wonder I was going nuts (relatively) alone.
When my mind was scanning env vars before, I totally missed this because the context of the other env vars surrounding it!
MAC=00FF6816060A
Make=LENOVO
Model=64758S4
NUMBER_OF_PROCESSORS=2
OS=Windows_NT
Well, let my thoroughness failure be a warning to all ThinkPad users working with Strawberry Perl.