Downloading problem

I'm facing a trouble in downloading, after completing 100% of the downloading I got notified that the downloaded is unable to finish. After that I followed the instruction of the web ,but the same problem reoccurred after trying a second time to finish downloading. Therefore I want to know what is the cause of this problem and how can I fix it. In addition I want to say that I have professional window XP 32x service pack 2, could this be the cause of the problem. Thank you waiting for your reply