I've had to change the default theme from the black and pink to the blue theme.
This is because the black and pink theme has suffered some sort of internet attack and had some dodgy code in it. Nothing to worry about, it's not a virus so no risk to any of your computers. We've not seen any evidence of it effecting any other themes so I've changed it to the one which was the 2nd most popular.
So nobody panic, but I wouldn't use the pink and black theme until we can either clean it up the problem or I can re-install the theme.