crash on start up

I load up and sometimes I get a black screen then flashes back to desktop to tell me the game has crashed and then it goes all black and unresponsive not alt-tab. So I have to use Ctrl alt delete to close the game. C++ trick done, spec are above ( worked until November, when i last played), Im, not sure if this is related but when it does load up and I create new world it gets stuck after in the Congratulations screen before it loads the game I left it running for 10 mins and nothing changed