Gday Brent
Yep, i Googled for three days.
You would be surprised how often it occurs
and the variety of reasons behind it.
ie registry hacks to the windows keycodes
add language bar back to desktop vs taskbar
malware keyloggers
video card drivers/control centres
and a whole range of MS KB articles.
I tried most of these with no joy.
Anyway, after three days i tried a safe boot and most of the keys still
wouldnt work so i retried the second keyboard, and this time it worked again

.
Put back the original and all keys but ctrl and most Fn are dead.
Use second board and all OK again.
I dont know what i did in those few days, but something i did must have uncorrupted something.
Andrew