Sometime in the last couple of weeks, Mathematica 10 Home Edition has picked up a little bug. Now every time it is launched, the message "Throw::nocatch: Uncaught Throw[False] returned to top level." is issued. I have reset Mathematica's options by starting with Shift+Option (this is on a Mac, running the very latest and greatest OS X 10.10.3) with no effect on the message. $Version is "10.0 for Mac OS X x86 (64-bit) (December 4, 2014)". I seem to be able to ignore this message and carry on as usual, but being of an inquiring mind, I do wonder what is behind it.