We use dropboxin our company. I have this problem in some pdf files, when i try to open those with adobe it says "cannot open, use restricted or forbidden". But i can open those files for example chrome browser. promblem occurs randomly in some files. I have no clue why this happens. Files usually have been zipped and i unzip thos with winrar. Somethimes porbplem is with filenames, but not every time.