By any chance, does this QVW try to output an HTML file (or any other type of file) through an onreload macro? If so, the outputted file needs to exist prior to reload in order for Qlikview to write to it. Otherwise, if there's no file output, check to make sure you have file creation permissions on the folder that the task is trying to output the file too.
Another thing that might be worth testing is this:
Open the document in QV Developer and go to Settings > Document Properties > General and change the Save Format compression from High to medium or none and try re-running the task. Does it return the same error message?
You might want to raise a case with QlikView support regarding this to have someone help you look into the matter.