A quick & dirty way of doing this is through the Access Protection settings in VSE.
Under the "User-defined Rules" you should be able to put in a "File/Folder Blocking Rule" and prevent their execution through there.
I'm sure there would be nicer (and scalable) ways to do it through HIPs, but i'm not that far ahead in my learning of the product.
Yes I saw that option but was unsure of how to do it.
Have given it a try just now and it appears to be what I am looking for.
thank you very much!