I had the same Problem with the IE Plugin and "solved" / bypassed it.
If the file name or the folder name contains special characters like a "#" you will be able to see the QVW in QEMC and set it up, you will as well be able to see respectively to list it in the QV access point, but when you try to open it the link will / can not be resolved propperly and so you will get your "Failed to open a Document. File not found".
Just take out the special characters (I replaced the "#" with a "_") and you will see that it works.
It is a bug in QlikView, and in Version 10 it is still there.