Facebook password required Mac pop up
I did a software update on my MacBook Pro (OS X Yosemite) today and ever since a window keeps popping up. The title on the window is "Facebook Password". The message inside the window says "Enter the password for (my email) in System Preferences." There are 2 options to click - Preferences and Cancel. Clicking Preferences does nothing and clicking Cancel only closes the box for a second or two before it pops back up again. Any suggestions on how to fix this?
Thanks
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MacBook Pro, OS X Yosemite (10.10.3)