David Blatner said:

I have never seen this happen when it was not a different version. Did you create the file with the SAME copy of InDesign, on the same computer, that you're trying to open it with? Are you sure you are running CS4? It is easy to launch CS3 by accident, for example.

yes cs4 is the only 1 i have on my computer and i did this all from home using no other computer or program but my own. some other files ive made in the past wont give me this problem but some are and i have no clue why