wont export video

[Curtis451]

 over the last view days I was able to  edit and upload my videos. But now it seems to be the cause where its failing to export the video.

this just didn't happen one time. it happen a month back. but than resolved it self. I played with the setting but that seemed to do nothing I rest my computer tried to export again  and it failed. I'm using the free version since I cant afford to buy the  full version  can you please tell me whats going on  I see other costumers having the very same problem.