Sorry to see that some of you are still having problems -I don't know if it will help but there are 2 things I did before Ep4 finally downloaded successfully for me:
1- I deleted the files in the Temp Folder (not the folder itself).
2- I launched the game in Administrative Mode (right click the game's shortcut on the desktop & click on "Run as administrator". I saw these tips on this forum & don't know if they actually helped - but they can't hurt either. Good luck...