I'm using Acrobat Pro 11.0.0 on Windows 10. Running an action to convert pdf to pdf/a. If an input folder is specified to process and the folder has a large number of files, the Action stops at about file #250 with an error message that a .dll file (sorry I didn't get the full file name) is missing or corrupt. Have to use Task Manager to close Acrobat. Works well if number of files is less than about 250.