Am hoping this saves someone some time...

I had a catastrophic drive failure last Friday. Fortunately Time Machine worked perfectly. However, after I restored onto a new boot drive, someone I work with noted that Dropbox says I deleted a file. I didn't, so I was confused, until I made the connection. Somehow the TM restore didn't restore the file (possibly it was damaged and so not backed up), and so DB thought I deleted it.

You may wish to set TM to not back up your Dropbox folder, or at least shared Dropbox folders, or if you go through this pain, review the files in DB carefully.