Hi Mauricio,
I've just updated my name, didn't realize I had that messed up :) .
I believe it's the IDE (plugin) because when I look at the "Process Instances" view, I can see 1 RuleFlowProcessInstance. However, when I double click on it to see its details in the "Process Instance" view, I get the above mentioned exception saying "Could not find process instance with id com.sample.evaluation".
Cheers,
Mike