Why can't I export my movie to any format or save it anywhere out of FCPX?

I have done it many times before however this time round, it will not let me export my project. I desperately need to export it to YouTube or Vimeo so that I can upload it to my A Level Media Blog.

I have Rendered All selection as I usually do, then went Share > Export Movie... but no screen comes up. I've also tried Share > to Youtube and Vimeo. Filled in my password etc and then the following appears on my screen:

I'm not entirely experienced with FCPX by the way. Somebody please help me!