Cursing myself...

My user account on my laptop has a password, and no one logs into it except me. But my son uses my computer as a 'Guest' from time to time and he can't see my Dropbox folder.

OOps!!!!

If you set your computer up with multiple accounts, each account can easily have its own dropbox. If you want more than one dropbox on the same account you need to change the location of the second one, then log out of the main one, log into the second one, then repeat the process when you are done with it...

But since dropbox files are also stored locally, any file you store there will be visible on your computer. You are better off having multiple accounts on that computer, with some files visible only to certain accounts. Then again, I don't see why you couldn't store the second dropbox on a stick or removal drive, which you would need to connect it before signing into the second account.

Yes, I do know all about backing up. I just didn't do it. Hence the self cursing. Now I'm several pages into a "this is what I remember happening in that story" outline.

Sorry to hear about that.
If you want to keep your work off a shared computer, I'd highly recommend Google Docs. I use it for my writing, and it's fast, easy to use and reliable.