HTTP Error When Uploading DOCX! Have Researched, Can’t Fix, Please Help!

I have been trying to upload few docx files since yesterday. I was able to do it last time I did it (maybe have been few months back). I can still upload images and pdf files (sometimes, even that failed too).

Please help. My solution now is to manually upload the file using FTP but that means other users can not use it and will not show on the Media Library.

TIA!

The page I need help with: [log in to see the link]