Have you tried putting the file on a portable device e.g. USB memory stick or Portable hard drive.
I sent a 2.5 Mb file to myself and tried to download it from another location. It indicated that it was scanning the attached file for viruses and then highlighted a clickable 'downoad file'. When I click on it, it seems to be busy doing something for not more than 1 second and then nothing. The file is nowhere to be found on my computer. This is weird. I downloaded a file sent from the same domain to the same domain the other day.