Difficulty with the editing mode

[AED-EWD]

I transferred a file from my floppy disk to my unix file(I believe this
is called uploading of a file). This file has 125211 characters and was
named mbox.9.When I used the vi command on the mbox.9, I got a surprise
response "mbox.9" Executable;and if I tried to work on the file while
in the vi edit mode,the file was reduced from 125211 of information down
to one line of information. I never had this problem before on the old
Gould 86 computer. We(the directorate) are now on a new system called
Pyramid;and I am using a WYSEpc. I was able to overcome the problem
by sending the troublesome uploaded file to myself and listing it
with a new name. I was able to use the vi command on the new name without
any problems. How come I could not use the vi command on this uploaded
file.