"Invalid Class" message

I am trying to open a file that was done by another designer, probably
in the orient, and when I try to open it, I get a message that says
"invalid class." I can see the part when this message come up. As soon
as I click "OK" the window closes on that part, and it's gone.
Is there any way to correct this problem so that I can use the file? I
need to work on it.
Thanks folks!