SOLVED (ish)
Well this was a weird one after removing pretty much every panel including all the rear seats I finally go to the bottom of the 'problem'.
It was never the car..
It seems that when either the front/rear brake pad sensor went weird on me (they're both physically fine) it rightfully triggered faults 005DE1 & 005DE0 in the DSC.
Now, here's the strange bit, it was the laptop COM1 latency settings that caused all the strange behaviour when trying to communicate with all the modules in ISTA/INPA. I've never changed that setting since I've setup the COM ports on the laptop and previously it's coped just fine. I can only assume that the DSC fault caused a lot more traffic on the CANBUS and it was tripping over the FTDI driver.
So, lesson is change your COM1 latency to as low as it can go as minie is now set to 1ms.
Now, back to the actual problem which is the sensors:
What causes both front and rear brake pad sensors to be tripped simultaneously?
When one gets tripped that both are registered as faulty? I know the rear one is ok as I checked it's resistance with an ohm meter.
Slowly getting there
Chris