Hopefully problem solved. Ran everything this afternoon for over an hour, no issues.
This time had laptop battery fully charged before I started. Seems trying to power all the accesories and recharge the laptop battery was a little too much.
Must now remember to ensure laptop is fully charged before I start a session. 
I am running active USB cables so will also look at adding a powered USB hub (5v, 500ma), that should also help with spreading the power drain.
Clear skies
Rod
