I'm having a weird and hopefully simple issue:

The sidebar dropdown menu in my Finder window is frozen/"grayed out". Consequently, I am unable to attach photos and other files into emails. For example, when I try to attach a photo from my iPhotos, I can navigate as far as the iPhotos folder and then am prompted to "Open" the entire folder without being able to access individual photos within.

Here is a screenshot of the problem:


Thanks in advance for any help. It's very appreciated!