Have you installed the InDesign 7.5.3 update? If you have the odds are this is either a corrupt file, or it isn't really IDML -- lots of users think changing a file extension changes the format, which it does not.
Either it’s not really an IDML file (I wish I had a dollar for every person that changed the file extension) or it’s corrupt.
There's that echo, again.
I just tried installing the 7.5.3 update as well. It opened on somebody else's version of CS5 and it's definitely and idml file.
What version of ID were they using to open the file? If it was the same version or newer as was used to create the file it would open a renamed .indd with a .idml extension.
A real IDML file would also open as Untitled, a renamed .indd would open as the named file.
They were using CS5 to test if it worked but they saved it from CC 2015. It seemed to work in her version of CS5
but I'll see if I can get her to save it as an idml again.
If it is an IDML file you should be able to do this:
- Make a copy of that file
- Exchange the IDML extension to ZIP
- Unzip it
- You will see several files now in the package.
If not, it is not an IDML file.