What’s Open is letting me know that I can’t eject the volume titled Disk Image until I close the photo called “cubs are number one.jpg.”

If you’ve ever worked with mounted volumes, such as flash drives or hard drives connected to your Mac, CDs or DVDs that you’ve inserted, or disk images that you’ve downloaded or created, you may have found yourself bumping your head against this rather uninformative error message. It’s trying to tell you that you’ve opened up a file directly from the mounted volume itself, but it doesn’t tell you which file is actually in use. And you can’t eject the volume until you figure it out.

What’s Keeping Me? ($5 donation requested, www.hamsoftengineering.com) and What’s Open (free, www.agasupport.com) are two applications that can help you solve this dilemma by showing you which files are currently in use on the volume of your choice.
You can also see what’s in use on any volume by launching Terminal and typing: lsof | grep volume-name (where volume-name is the name of the disk that you’re trying to eject).