My girlfriend experiences the following strange behavior on her MacBook Pro running on Yosemite. It does not happen all the time but when it does, things are always the same:
She closes all the opened documents from apps like ms-word, Adobe Acrobat Reader or Adobe Indesign and then tries to open a new one from the
finder window. It looks like the document will be opened, but it doesn't.
The app is still running but the file is not opened.
Opening it from the
File menu still works, though.
When this happens she also cannot close the app neither from the
File menu nor the
Dock. She needs to go to
Activity Monitor and force quit the app.