Sorry, my first guess was that you tried to open a file of the current version P8 using an older version of Prime.
I looked at the file and its a damaged corrupt archive (Prime mcdx files are just renamed zip archives). I was able to save some of the contents, but there seems at lot to be missing, amongst them all pictures. I could recover most pictures but wasn't able to get Prime to use them in the file. So I attach the pics in a separate archive (media.zip) along with the mcdx file.
Maybe someone else has more luck in recovering the file.
