what OS and what version of winrar do you have? Go to
http://www.rarsoft.com/download.htm and get the latest version there. Winrar 3.42 will open this fine.
Definitely something is odd with this file though if a number of people are having issues. I just tested opening it on win2k, win98 and linux machine and it opened fine. However, when using a very old winzip, I did run into errors. So be sure to get the latest version.