Persistent "Google sign-in" error, even with correct password

I believe this started after I installed the Google+ app, but there is a constant notification that looks like a warning sign, and it displays this:

Entering the correct password does not dispell it (it's the same password every other Google app uses, and only one is complaining). Also, every Google app still works, each one acts as if I'm still signed in. So where is this coming from, and how can I get rid of it?

Update: I have tried both clearing the data for the Google+ app (which helped for about a half hour) and actually resetting my password and using the new one. Neither worked.

Answer

I had the same problem. My solution was to uninstall and reinstall Google+ and everything worked fine after that.