Unity does not handle OSX dot underscore ".foo.bar" system files well on Windows
If project contains "..bar" and "._.bar.meta" files errors for each file will be thrown. For example:
"Refresh case sensitivity failure. Asset: Assets/._ShopWindow.png ; Metafile: Assets/._ShopWindow.png.meta"

"assets/._shopwindow.png is not a valid asset file name. Please make sure there are no slashes or other unallowed characters in the file name. The file will be ignored."

This creates minor inconvenience when sharing projects between OSes.

Read more about these files here: http://apple.stackexchange.com/questions/14980/why-are-dot-underscore-files-created-and-how-can-i-avoid-them