This often happens if you have downloaded to a location too "far away" from your Desktop thus the path is too long to unzip
1) Try to move the download directly onto your desktop and unzip there
2) Try to unzip using winRAR (another powerful "unzipper" ) which should be standard on all window machines - Can be downloaded here: http://rarlab.com
3) Finally you should try to reboot your "puter" since windows needs to sleep a little every 24 hours