Just to add in case relevant. I have encountered the same problem. It happened that I was trying to unzip the scorm file from a server where the moodledata is not located. To elaborate further, I have 2 (or more servers). The moodledata is located in one of the server while another server accesses the data via network shared drive.
When I tried to extract the file from the server which moodledata is not located, it gave me the problem. Once I switched to the server where the file is located, then the problem resolved.
I am not sure about later version of Moodle, but any version of Moodle 1.9.x have problem to unzip file if the moodledata is not located in the same server.