Ok, I'm going to cut the grass. ( and maybe find an all new and interesting use for the clippings!)

So, Dave, I built EXACTLY the test code you posted. No more, no less. Using the following:
MCS 2.3.0
PBPro 2.47
MPASM 5.03
Epic Plus

Code:
DEFINE OSC 4

ANSEL=%00000000
CMCON=7

LOOP:

HIGH GPIO.2
PAUSE 100
LOW GPIO.2
PAUSE 100

GOTO LOOP
No errors, no warnings. Device programs just fine. Led blinks more or less where and when it should on the programmer. Splash returns with "fat dumb and happy". Insert the chip into the proto board socket, power it up, no run. Verified, tested each and every power feed, ground, led operation, 5v across the chip just as it should be.
As my boss would say, and with appologies to anybody, wtf.