I'm having a problem with dropbox. I've recently added a user to 2 of my dropbox folders (for group works), and from then all files uploaded by anybody in those folders are "duplicated" (just once) with a file of the same type (.pdf, .jpg, ...) all of the same size of 4 kb (no matter the dimension of the original files), and with the same name with "._" in front of each name. None of the duplicates are openable by their corresponding software.
I've never had this problem before, and none of the other participants in those folders had it either (before now), apart from the one I've mentioned above. Also, none of my other folders in dropbox have this problem, so I've deduced that he is the origin of the problem.
Now, he uses a Macbook, while the rest of us use windows OS (on Asus, Hp, ...), but I've already added mac users before in other folders without this problem, which is very annoying (especially in subfolders with dozens of files, and considering that also the subfolders themselves have a corresponding duplicate).
One more thing, they are deletable, but soon they come back just where they were. (Maybe a case of 'the cat came back'? ^^' Sorry, couldn't resist)
I didn't find anything about it on google, just mentions about multiple duplicates, but this is not the same, I think.
Please help me, I don't know what to do about it.