"Change in connectivity detected"

Hi - With Octopus 0.2, I am getting this message a few minutes after pressing start:

"Some change in connectivity was detected. To be sure not to crash on the next run, please reset".

It then stops at the end of generation 0. 

After pressing start I do not change anything  in the GH definition, or in the Octopus window... I am not sure why this message is coming up.

Any help gratefully received.  

Fred