Several Issues Saving Movies

Hi I've been working on a video project and it's been a pain in my **** the whole way through, and now it's not saving as a video. I've tried saving it as a video file for Windows 8, but my computer keeps overheating and shutting down when I do. I've tried saving it as a Windows Media file, but it gives me an error code. I've tried saving it as a Youtube video, on OneDrive, on Facebook, but they all give me the error code (0x8004889C). I realize that there are loads of people who've asked about this particular error code, but none of the methods they've used have helped me. I run the 2012 version. Please help!