I've opened my Multibit wallet after several days and noticed it has been cleared while being closed and under password. There is no way anyone could have access to my Mac or had my password. How could this happen at all?  I'm quite new to the game but I suppose there is no much I can do about it, however I cannot understand how is this possible... I've tried to google the issue but found just 1 user claiming the same so far... Any clue?