Cannot open corrupted file

Every time I down load a new map and then attempt to open it I get a “Cannot open corrupted file” I’ve done this a dozen times with the same results. Not sure what I’m doing wrong I follow it step by step. Does anyone know how to fix my problem? Thanks.

Troy, I moved your question to a new topic because it doesnt belong in the FAQ list.
Can you specify what you mean by “attempt to open it”. What file do you open exactly and with which programm?