As with many other errors, this error can be extremely frustrating. There's a fix that works most of the time according to my own research.
Don't worry, it's a pretty easy fix.
Go to your "shared" folder. It should be located somewhere like this:
Go into the "Start" folder
Choose the version of FL Studio that you're working with (in case you have many installed). In my case it's FL Studio 12
Double click the Reset settings and watch the magic happen.