the frenquently cause was the uncorrect format of file paf (i.e "dcam.paf.paf")
Give more attention if your operative system don't show the file format ( you can change the parameter in folder option)
-all the folder(i.e. dcam, products, temp,) and subfolder haven't the right access.
-kind of user(user, administrator ...)
-sorry for my english!!!