Supplied Illustrator file layers corrupt with unrecognisable names

Hi, 

I had been supplied an illustrator file from an artist that had their work separated into layers. There were then some amends to the file and it was resupplied by the artist, however in this new file all the items seem to have been split into layers with unrecognisable layer names and the original layers had disappeared. The artist is using CS5 and i convert the file to latest version V25.4.1 (what ever that is in CS!). 

Can anybody shed any light on this, please see attached screen grabs of how the layers came through on the original file and the new file.

Thanks,

Martin