ERA: What does "Data Field Is Not Running" mean as an error?

I mean, obviously, it means that the data field is not running... but if so why is it trying to evaluate code and so generating an error report?

Does that mean something has crashed at an earlier point?

Any pointers on what that might be and how to find out anything else about it?

Thanks,

Gaius

PS: Lest I'm being too obscure, this is based on an error log I can see in the ERA tool. It gives me an occasional error on specific fields on a line that appears to be calling DataField.getObscurityFlags()!