I re-downloaded the online zip just to double check the zip I have on my computer. I verified that have no problems extracting any of the files, and neither did the testers. 

However, if I try to extract to the zip file, like as it appears above, I do get a very similar error message like the one you pasted. Maybe you need to double check the path where you are extracting the files to.  Do you use WinZip?

I really don't understand why else you would be having a problem, since I can't seem to duplicate (unless I use an extraction path to a zip file).