I wonder if this was some ICO issuing unannounced refunds? It came in over a week ago but I just now noticed it:
0x78482281699b48dd34a2d521D1fE1E6e22e25314
Can you list the amount of ICO that you have invested at pretty much ever? It's funny because some people went compulsively investing on every single ICO in town during the ICO hype thing and a some of them never got anywhere, this made people get their ETH back a ton of time later and they didn't even knew that invested on there. Some people isn't able to track back what exactly they invested at and what amount because they went into a ton of ICOs.
Well, they know who you are now!!! You can google the address and it comes up a bunch of time, I came across this (slightly unrelated) nearly made me cry
https://github.com/bokkypoobah/EthereumFoos#dont-leave-your-ports-openone of the results was listed in bokkypoobah's github - perhaps you could ping him and he might help - some attack.
Do be careful though - sounds like the opening scene of a B movie.