file access

Greetings.. i am using following codes to run multiple threads at a time to get data from different links and save the data to different file as well. As the file name/path is different for each loop? i don't understand why it throws following exception: The process cannot access the file...

I'm struggling a bit with folder permissions. I want to basically add a AD group to a folder with modify access but then restrict it. Problem is I couldn't figure out how to apply a permission to "this folder only" The goal is to set the following restrictions to a main folder: deny delete...