An update for today, and I'm happy to say a successful one although it also brings with it another question.
Simply because it was an easy test, I first left the batteries disconnected overnight but there was no positive change today. Which I pretty much expected buy hey it was an easy test.
So next I used my other laptop (running W7 build 154) and flashed the same stock tune in from the external drive I used yesterday (same one I tried yesterday with no success) and now it works fine?? TCC functions work perfect in both normal and tow/haul so everything is back to normal. My question is- what is or was the issue? Possibly something on my other laptop (running XP BTW) that I have always used with no issues? Perhaps I should un-install everything on it and re-install? Could all the tunes on it be compromised as well?
Sorry, I guess that's more than a single question.